UITableView with Segmented Controller not displaying data immediately - Swift - swift

I have a Tab Bar Controller, and one of the two views from it is a TableViewController. The TableViewController has a SegmentedControl bar on the top of the table to switch between two datasets pulled from Firebase.
When I run the app, the table doesn't show any data straight away, only when I switch to the other segment of the SegmentControl bar. But, when I switch back, the data for the first segments loads.
I put in a breakpoint to see what was happening, and it was skipping over the code I wrote to pull the data from Firebase, so the arrays were empty upon initial loading, hence the lack of data. Yet, when I switch segments to the other option, the data appears.
I'm also trying to sort the data within the arrays, and this doesn't do anything at all because it runs when the arrays come back empty, so there is nothing to sort.
My code is:
class LeaderboardViewController: UITableViewController
{
#IBOutlet weak var segmentedControl: UISegmentedControl!
#IBOutlet var leaderboardTable: UITableView!
var countyRef = Database.database().reference().child("countyleaderboard")
var schoolRef = Database.database().reference().child("schoolleaderboard")
var refHandle: UInt!
var countyList = [County]()
var schoolList = [School]()
override func viewDidLoad()
{
super.viewDidLoad()
fetchData()
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
var sectionCount = 0
switch(segmentedControl.selectedSegmentIndex)
{
case 0:
sectionCount = countyList.count
break
case 1:
sectionCount = schoolList.count
break
default:
break
}
return sectionCount
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
let boardCell = tableView.dequeueReusableCell(withIdentifier: "boardCell", for: indexPath)
switch(segmentedControl.selectedSegmentIndex)
{
case 0:
boardCell.textLabel!.text = "" + countyList[indexPath.row].name! + ": \(countyList[indexPath.row].score!)"
break
case 1:
boardCell.textLabel!.text = "" + schoolList[indexPath.row].name! + ": \(schoolList[indexPath.row].score!)"
break
default:
break
}
return boardCell
}
func fetchData()
{
schoolRef.observe(.childAdded, with:
{ snapshot in
if let dictionary = snapshot.value as? [String: AnyObject]
{
let school = School()
school.name = dictionary["name"] as! String
school.score = dictionary["score"] as! Float
self.schoolList.append(school)
}
}, withCancel: nil)
self.schoolList.sort(by: { $0.score > $1.score })
countyRef.observeSingleEvent(of: .value, with: { snapshot in
for child in snapshot.children
{
let snap = child as! DataSnapshot
let county = County()
county.name = snap.key as String
county.score = snap.value as! Float
self.countyList.append(county)
}
})
self.countyList.sort(by: { $0.score > $1.score })
DispatchQueue.main.async
{
self.leaderboardTable.reloadData()
}
}
#IBAction func segmentedControlChanged(_ sender: Any)
{
DispatchQueue.main.async
{
self.leaderboardTable.reloadData()
}
}
}
My questions are:
Why does the data not load straight away?
Where are the arrays coming from if they are not being populated with data on the first run? And why are they not being sorted if that code is directly below the code that populates them?

The dispatch block should be after the for loop and before the }).
It should be within the observe/observeSingleEvent. Also your sort code needs to be inside the same block. Like below:
countyRef.observeSingleEvent(of: .value, with: { snapshot in
for child in snapshot.children
{
let snap = child as! DataSnapshot
let county = County()
county.name = snap.key as String
county.score = snap.value as! Float
self.countyList.append(county)
}
self.countyList.sort(by: { $0.score > $1.score })
DispatchQueue.main.async
{
self.leaderboardTable.reloadData()
}
})

Related

Tableview Updating wrong cell

I made a like button problem is when the like button is tapped the values update only the first tableview cell even if I clicked the second cell it will update the values of likes in the first tableview cell. The values update properly on firestore for each individual cell but its being loaded wrong
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
motivationThoughts.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "DailyThoughtCELL", for: indexPath) as? dailyMotivationTableViewCell
cell!.generateCellsforDailymotivation(_MotivationdataMODEL: self.motivationThoughts[indexPath.row], objectID: self.motivationThoughts[indexPath.row].motiveID)
//cell!.postID = self.motivationThoughts[indexPath.row].motiveID //this works and updates the value
//cell!.generateLikeCell(objectID: self.motivationThoughts[indexPath.row].motiveID)
return cell!
}
func loaddailymotivation() {
FirebaseReferece(.MotivationDAILY).addSnapshotListener { querySnapshot, error in
guard let snapshot = querySnapshot else {
print("Error fetching snapshots: \(error!)")
return
}
snapshot.documentChanges.forEach { diff in
if (diff.type == .added) { // this line means if the chage that happened in the document was equal to added something
let data = diff.document.data()
print("we have\(snapshot.documents.count) documents in this array")
let dailyMotivationID = data["objectID"] as! String
let dailymotivationTitle = data["Motivation title"] as! String //calls the data thats heald inside of motivation title in firebase
let dailyMotivationScripture = data["daily motivation scripture"] as! String //calls the data thats heald inside of Motivation script in firebase
let dailyMotivationNumberOfLikes = data["Number of likes in daily motivation post"]as! Int
let MdataModel = motivationDailyModel(RealMotivationID: dailyMotivationID, RealmotivationTitle: dailymotivationTitle, RealmotivationScrip: dailyMotivationScripture, RealmotivationNumberOfLikes: dailyMotivationNumberOfLikes)
self.motivationThoughts.append(MdataModel)
}
/*
I thinkyou need a method that identifies the item that needs to be modified in the array, and replace/modify it. If you add a new object, you have one more element in your table*/
if (diff.type == .modified) {
print("Modified data: \(diff.document.data())")
let newdata = diff.document.data()
let objectID = newdata["objectID"] as! String // we get the object id of the uodated item
//self.GrabThatDamnstring(grabIt: objectID)
//self.incrementLikes(NewobjectID: objectID) //write a function to grab the string from the certain post and then send it to dailymotivationviewcell into the function increment likes so so it can update the specific objectID
guard let dailymotivationIndex = self.motivationThoughts.firstIndex(where: {_ in objectID == objectID}) else { return }
var dailymotivation = self.motivationThoughts[dailymotivationIndex]
let dailyMotivationNumberOfLikes = newdata["Number of likes in daily motivation post"] as! Int
dailymotivation.motivationNumberOfLikes = dailyMotivationNumberOfLikes
self.motivationThoughts[dailymotivationIndex] = dailymotivation
// here you will receive if any change happens in your data add it to your array as you want
}
DispatchQueue.main.async {
self.tableview.reloadData()
}
}
}
}
this is the uitableview cellcode
import UIKit
import FBSDKLoginKit
import Firebase
import JGProgressHUD
class dailyMotivationTableViewCell: UITableViewCell {
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
//numberOfLikesGenerator()
self.holdView.layer.cornerRadius = 19
self.likedbuttonFIlled.isHidden = true
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
#IBOutlet weak var holdView: UIView!
#IBOutlet weak var likedbuttonFIlled: UIImageView!
#IBOutlet weak var likeSavedButton: UIButton!
#IBOutlet weak var DMtextLabel: UILabel!
#IBOutlet weak var DMtitleLabel: UILabel!
#IBOutlet weak var numberOfLikesLabel: UILabel!
//MARK: VARS/LETS
var postID : String!
var MotivationData : motivationDailyModel!
let hud = JGProgressHUD(style: .light)
//MARK: IBACTIONS
#IBAction func likeButtonTapped(_ sender: Any) {
if (Auth.auth().currentUser != nil || AccessToken.current != nil) {
changeLikeButtonMode()
//update like number and update like number on firebase
}
else{
hud.textLabel.text = "Please Login to Continue!"
hud.show(in: self.contentView)
hud.dismiss(afterDelay: 3.0)
hud.indicatorView = JGProgressHUDErrorIndicatorView()
//no user login so pull up login view
}
//MARK: TODO when this button is tapped ALSO WANT TO STORE THIS SNAPSHOT INTO AN ARRAY THAT WE WILL SHOW IN OUR SAVED VIEW CONTROLLEr
}
//call this function from motivation daily viewcontroller and it will also have the item that was tapped
func incrementLikes(){
//MARK: WE NEED TO FIND OUT HOW WE GET THE UUID FOR THE CERTAIN POS
FirebaseReferece(.MotivationDAILY).document(postID).updateData(["Number of likes in daily motivation post":FieldValue.increment(Int64(1))]) { (error) in
if error != nil {
print(error!.localizedDescription)
} else {
print("successfully incremented data!")
}
}
}
func changeLikeButtonMode(){
// so if likedbutton is tapped and the heart isnt red that means that the tag is = 0 so its gnna show the red heard and then also change the tag to 1 but when it is tapped again its going to change the tag to 0 and removed the red heart
if likeSavedButton.tag == 0 //means its empty
{
incrementLikes()
self.likedbuttonFIlled.isHidden = false
likeSavedButton.tag = 1
}else {
self.likedbuttonFIlled.isHidden = true
likeSavedButton.tag = 0
}
}
//MARK: FUNCTIONS
func generateCellsforDailymotivation(_MotivationdataMODEL : motivationDailyModel,objectID : String!) {
DMtextLabel.text = _MotivationdataMODEL.motivationDailyScripture
DMtitleLabel.text = _MotivationdataMODEL.motivationTitle
numberOfLikesLabel.text = "\(String(_MotivationdataMODEL.motivationNumberOfLikes))"
postID = objectID
}
}
The condition in your guard statement always evaluates to true
guard let dailymotivationIndex = self.motivationThoughts.firstIndex(where: {_ in objectID == objectID}) else { return }
Try this instead
guard let dailymotivationIndex = self.motivationThoughts.firstIndex(where: { $0.RealMotivationID == objectID}) else { return }

When to detach firebase listeners in tableView cell?

In chat app, in order to keep track of each chat's last message and unread messages for each user participating in chat, when the tableView cell is dequeued I am attaching a .childChanged listener on the cell. When the listener is fired, I update the chat label.text on each row for the corresponding chat.
When should I remove these listeners or what is the best practice to update the chat in the cell in my case?
What is the flow of the program?
1. Download current user
2. Download current user chatIDs
3. Download chat for each chatID
4. Populate tableView with chats
5. In each cell observe childChanged at
chats/chat.chatUID/currentUserUID/.observe(.childChanged)
6. If "unreadMessagesCount" was changed, update it on the cell
class ChatTableViewCell: UITableViewCell {
#IBOutlet weak var lastMessageLabel: UILabel!
var chat: Chat! {
didSet{
self.updateUI()
}
}
func updateUI() {
self.chat.observeChildChanged(chat: self.chat, currentUserUID:user.userUID) { (lastMessage, unreadMessagesCount) in
if !lastMessage.isEmpty{
self.lastMessageLabel.text = lastMessage
}
if unreadMessagesCount > 0 {
self.lastMessageLabel.font = UIFont.boldSystemFont(ofSize: 16.0)
self.chatUnreadMessagesCount.text = "\(unreadMessagesCount)"
} else {
self.lastMessageLabel.font = UIFont.systemFont(ofSize: 15.0)
self.chatUnreadMessagesCount.text = ""
}
}
}
}
class MessagesViewController: UITableViewController {
override func viewDidLoad() {
//observe ~/users/uid
DDatabaseRReference.users(uid: uid).reference().observeSingleEvent(of: .value, with: { (snapshot) in
guard snapshot.exists() else {return}
if let userDict = snapshot.value as? [String : Any] {
self.currentUser = UserModel(dictionary: userDict)
self.userWasDownloaded = true //this will trigger the setter and start downloading chatId's of current user
}
})
}
var userWasDownloaded: Bool {
get {
return true
}
set {
self.fetchChatsIdsOf(currentUser: self.currentUser)
self.tableView.reloadData()
}
}
func fetchChatsIdsOf(currentUser: UserModel) {
//get chatIds of currentUser from ~/users/currentUser.userUID/chatIds
DDatabaseRReference.users(uid: currentUser.userUID).reference().child("chatIds").observe(.childAdded, with: { (snapshot) in
let chatUID = snapshot.key
if !self.chatIdsDownloaded.contains(chatUID) {
self.chatIdsDownloaded.append(chatUID)
}
})
}
//after chatIdsDownloaded is set,
//download the new chat for the last chat appended to chatIdsDownloaded array
var chatIdsDownloaded = [String]() {
didSet {
guard let chatID = chatIdsDownloaded.last else {return}
self.downloadNewChat(chatID: chatID)
}
}
func downloadNewChat(chatID: String) {
DDatabaseRReference.chats.reference().child(chatID).observeSingleEvent(of: .value, with: { (snapshot) in
......
self.currentUserChats.insert(chatChecked, at: 0)
}
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ChatTableViewCell", for: indexPath) as! ChatTableViewCell
cell.chat = currentUserChats[indexPath.row]
return cell
}
}
chats // <- all chats in the app for all users in the app
-LOMVtcjOEOu2p1apMKV
chatUID: "-LOMVtcjOEOu2p1apMKV"
isGroupChat: true
lastMessage: "Katherine Gregory has joined the group"
lastUpdate: 1539761870.2237191
+users
IN4pgCS5NqQZZLpdmoz1KeDiFqj2
fcmToken: ""
firstName: "Alex"
userUID: "IN4pgCS5NqQZZLpdmoz1KeDiFqj2"
unreadMessagesCount: 5
users // <- all users in the app
IN4pgCS5NqQZZLpdmoz1KeDiFqj2
+chatIds
-LOMVtcjOEOu2p1apMKV: true
- name: ""
- email: ""
...etc
You can check if you added 2 or more observers for cell.
Add breakpoint or print() here:
self.chat.observeChildChanged(chat: self.chat, currentUserUID: user.userUID) { (lastMessage, unreadMessagesCount) in {
//breakpoint or print("observeChildChanged")
...
}
Please, reuse your cell.
Send new message.
If you have 2 or more messages it means that you have not set only one observer.
Perhaps this approach is not perfect, but it can help you (remove old observers before add new):
var chat: Chat! {
didSet {
self.removeOldObserver()
self.updateUI()
}
}
func removeOldObserver() {
...
}
As Jay suggested, I am attaching .childChanged observer on each chat newly downloaded.
However, if I go to firebase console and update the value of a child at ref path, childChanged observer is not always triggered. Sometimes, it works, sometimes it does not What could be the problem?
I am using break points on all lines and none of them is hit when value is changed in database.
example: name:"Alex"
change with: name: "John"
UPDATE
This answer is correct, I had forgotten to delete my previous implementation in which was detaching the listeners in prepareForReuse()
var currentUserChats = [Chat]() {
didSet(newValue){
attachChildChangedObserverOn(chat: newValue)
}
}
var observersArray = [String: UInt]() // chatUID:handle
func attachChildChangedObserverOn(chat: Chat) {
var handle: UInt = 0
let ref = DDatabaseRReference.chats.reference().child(chat.chatUID).child("users").child(currentUser.userUID)
handle = ref.observe(.childChanged, with: {[weak self] (snapshot) in
self?.observersArray[chat.chatUID] = handle
print("snapshot.value is \(snapshot.value) and snapKey is \(snapshot.key)")
guard snapshot.exists() else {return}
let chatChanged = chat
var lastMessage = ""
var unreadMessagesCount = 0
var lastUpdate = 0.0
switch snapshot.key {
//case....
}
})
}

Fatal Error: Index out of range - Swift 4 and Firebase

I am creating an iOS application using XCode 8 and Swift 4 that keeps track of events. I am using Firebase as my database tool for this app. I am running into an "index out of range" error in the code below. I am using a for loop to read the Event start and end times for each event in the Firebase Database. The code is able to return the event names, but not the times underneath. Why is this the case? Is there something wrong with my code, or is there something wrong with my database structure? The database structure used is pasted below the code here.
Code here:
import UIKit
import Firebase
import FirebaseAuth
import FirebaseDatabase
class Event_List_Controller: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var tableView: UITableView!
var eventList = [String]()
var startTimeArray = [String]()
var endTimeArray = [String]()
var ref: DatabaseReference?
var handle:DatabaseHandle?
override func viewDidLoad() {
super.viewDidLoad()
endTimeArray.removeAll()
tableView.delegate = self
tableView.dataSource = self
let emailfinal = UserDefaults.standard.string(forKey: "splicedEmailStandard")
ref = Database.database().reference()
handle = ref?.child(emailfinal!).child("Event Data").observe(.childAdded, with: { (snapshot) in
if let item = snapshot.value as? String {
self.eventList.append(item)
self.tableView.reloadData()
}
})
// FOR LOOP THAT POPULATES THE START AND END TIMES
for individualEvents in eventList {
ref = Database.database().reference()
handle = ref?.child(emailfinal!).child("Event Data").child(individualEvents).child("Start Time").observe(.childAdded, with: { (snapshot) in
if let item = snapshot.value as? String {
self.startTimeArray.append("\(item)")
}
})
handle = ref?.child(emailfinal!).child("Event Data").child(individualEvents).child("End Time").observe(.childAdded, with: { (snapshot) in
if let item = snapshot.value as? String {
self.endTimeArray.append("\(item)")
}
})
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return eventList.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = self.tableView.dequeueReusableCell(withIdentifier: "customClassCell") as! CustomTableViewCell
cell.classLabel.text = eventList[indexPath.row]
// FATAL ERROR: INDEX OUT OF RANGE HERE.
cell.timeLabel.text = "\(startTimeArray[indexPath.row]) - \(endTimeArray[indexPath.row])"
return cell
}
}
Database Structure:
email#email (User)
-> User Information
----> (Information)
---> Event Information
------> Event Name
----------> Event Start Time
----------> Event End Time
----------> Event Location
email#email (User 2)
----> ...
It looks like you're calling reloadData() before you're actually getting the start and end times for the events, so the startTimeArray and endTimeArray will not have objects at the index of the event you just got from firebase.
Also consider that with Firebase you're setting up observing rather than getting all of your data at once. Perhaps some simple class like Event:
class Event {
var name: String
var startTime: String
var endTime: String
init(name: String) {
self.name = name
self.startTime = "" //or some other sensible default before loading
self.endTime = "" //or some other default
}
}
Then have an array of Event object that your tableview is using instead of the array of strings, and update the Event objects and refresh the table view whenever you get new data in from Firebase

UISearchBar textDidChange data from plist

I'd like to search through items of my plist. The plist consists of an array of dictionaries. Each key/value represents Strings/Ints, etc but that isn't important.
As you'll see in the tableViewController class below, I've currently got an array that I have typed. I know I need to make an array of objects/items from my plist but I can't work out how to reference objects from the plist in the view controller.
View controller.swift file:
import UIKit
class TableViewController: UITableViewController, UISearchResultsUpdating {
var array = ["Example 1", "Example 2", "Example 3"]
var filteredArray = [String]()
var searchController = UISearchController()
var resultsController = UITableViewController()
override func viewDidLoad() {
super.viewDidLoad()
searchController = UISearchController(searchResultsController: resultsController)
tableView.tableHeaderView = searchController.searchBar
searchController.searchResultsUpdater = self
resultsController.tableView.delegate = self
resultsController.tableView.dataSource = self
}
//Added func to update search results
func updateSearchResults(for searchController: UISearchController) {
filteredArray = array.filter({ (array:String) -> Bool in
if array.contains(searchController.searchBar.text!) {
return true
} else {
return false
}
})
resultsController.tableView.reloadData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
extension TableViewController {
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if tableView == resultsController.tableView {
return filteredArray.count
} else {
return array.count
}
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell()
if tableView == resultsController.tableView {
cell.textLabel?.text = filteredArray[indexPath.row]
} else {
cell.textLabel?.text = array[indexPath.row]
}
return cell
}
}
I've tried solving this by creating an object class from a tutorial on plists. It uses the example of a periodic table of elements:
import UIKit
struct Element {
enum State: String {
case Solid, Liquid, Gas
}
let atomicNumber: Int
let atomicWeight: Float
let discoveryYear: String
let group: Int
let name: String
let period: Int
let radioactive: Bool
let state: State
let symbol: String
// Position in the table
let horizPos: Int
let vertPos: Int
}
extension Element {
enum ErrorType: Error {
case noPlistFile
case cannotReadFile
}
/// Load all the elements from the plist file
static func loadFromPlist() throws -> [Element] {
// First we need to find the plist
guard let file = Bundle.main.path(forResource: "Element", ofType: "plist") else {
throw ErrorType.noPlistFile
}
// Then we read it as an array of dict
guard let array = NSArray(contentsOfFile: file) as? [[String: AnyObject]] else {
throw ErrorType.cannotReadFile
}
// Initialize the array
var elements: [Element] = []
// For each dictionary
for dict in array {
// We implement the element
let element = Element.from(dict: dict)
// And add it to the array
elements.append(element)
}
// Return all elements
return elements
}
/// Create an element corresponding to the given dict
static func from(dict: [String: AnyObject]) -> Element {
let atomicNumber = dict["atomicNumber"] as! Int
let atomicWeight = Float(dict["atomicWeight"] as! String) ?? 0
let discoveryYear = dict["discoveryYear"] as! String
let group = dict["group"] as! Int
let name = dict["name"] as! String
let period = dict["period"] as! Int
let radioactive = dict["radioactive"] as! String == "True"
let state = State(rawValue: dict["state"] as! String)!
let symbol = dict["symbol"] as! String
let horizPos = dict["horizPos"] as! Int
let vertPos = dict["vertPos"] as! Int
return Element(atomicNumber: atomicNumber,
atomicWeight: atomicWeight,
discoveryYear: discoveryYear,
group: group,
name: name,
period: period,
radioactive: radioactive,
state: state,
symbol: symbol,
horizPos: horizPos,
vertPos: vertPos)
}
}
And in the viewController class, instead of having
var array = ["Example 1", "Example 2", "Example 3"]
I've tried variations of
var array = Element["name"]
and
var array = elements.name
But they obviously don't work because the reference to the plist is in the object class.
If anyone has any idea on how to solve this using swift 3/xcode 8 I would be very appreciative!!
I hope your question is still relevant. As I understand, you can't filter your array, right? If so, I recommend you to take a look at this and this tutorials. Both of them are representing a little bit different approaches to load filtered array, but it doesn't matter much, they work.
P.S. I don't recommend you to make a special tableView for searching, if you want to customize it hereafter, because you will have to do it programmaticly later.
It will be more efficiant to do like this:
If searchController.isActive {
// do some stuff
} else { // another stuff }
But it is just my opinion. I hope my question will help ;).
Thanks for the links Oleg. They were really good!!
It wasn't so much the filtering I had a problem with but actually parsing objects from my plist into a tableview. It took me a few days but I found an answer in case other people were also having the same problem. Keep in mind I'm reasonably new to this and so it might not be the best/perfect way of doing it but it works.
In viewDidLoad, I made a reference to the plist using the following code:
let path = Bundle.main.path(forResource: "Elements", ofType: "plist")
let dictArray = NSArray(contentsOfFile: path!)
I'm not sure of the relevance but I'm pretty sure this next bit is needed if the plist ever needed to be updated. (Also in viewDidLoad)
for elementItem in dictArray! {
let newElement : Element = Element(state:((elementItem as AnyObject).object(forKey: "state")) as! String,
atomicNumber:((elementItem as AnyObject).object(forKey: "atomicNumber")) as! Int,
atomicWeight:((elementItem as AnyObject).object(forKey: "atomicWeight")) as! Float,
discoveryYear:((elementItem as AnyObject).object(forKey: "discoveryYear")) as! String
etc. for each of the keys in the dictionary in the same order as in the Element object in the question. Then (also in viewDidLoad):
elementsArray.append(newElement)
Then its pretty easy, in cellForRow I just have to make a new variable that refers back to the object and I can call up each/any of the associated dictionary keys. E.g.:
let element : Element
cell.textLabel!.text = element.name
cell.detailTextLabel?.text = element.symbol
return cell
Like I said, I know its not perfect but it worked for me. I've heard its not best practice to put too much information in viewDidLoad, so someone else might be able to confirm or provide a better answer.

FetchedResultsController Swift 3 API Misuse: Attempt to serialize store access on non-owning coordinator

I'm attempting to use a fetchedResultsController to handle the results in my UITable.
It works initially when the program starts up. Then when I switch back to the inventory tab where my table is (for the viewToAppear again), this is when it crashes.
I'm getting a runtime crash error in my viewWillAppear() method of the window which has the table.
In particular it crashes on the Inventory+CoredataProperties.swift file on this line let characters = name!.characters.map { String($0) }, but I suspect the error is somewhere else as this works initially so why not now on the 2nd reload?
Here is the function.
override func viewWillAppear(_ animated: Bool) {
print("view appearing")
//When the view appears its important that the table is updated.
//Trigger Event on SearchBar in case returning from BarCode Scanner
// self.searchBar:SearchBar textDidChange:recentlySearchedWord;
//searchBar.performSelector(":textDidChange")
//Perform another fetch again to get correct data~
do {
//fetchedResultsController. //this will force setter code to run again.
print("attempting fetch again, reset to use lazy init")
fetchedResultsController = setFetchedResultsController() //sets it again so its correct.
try fetchedResultsController.performFetch()
} catch {
print("An error occurred")
}
inventoryTable.reloadData()//this is important to update correctly for changes that might have been made
}
The error occurs on the try fetchedResultsController.performFetch() statement. I'm getting a lot of errors before the actual crash occurs saying "API Misuse: Attempt to serialize store access on non-owning coordinator (PSC = 0x170265300, store PSC = 0x0). I've been refactoring my code to work with the new swift 3 standards I have a feeling I did something wrong or maybe something changed with how the fetched results controller works.
Any help is appreciated as to what could be the cause?
If you think I'm missing a file you need to see, just let me know and I'll add it to the relevant source code below.
POSSIBLE RELEVANT SOURCE CODE BELOW:
InventoryController.swift (Entire File)
import UIKit
import CoreData
import Foundation
class InventoryController: UIViewController, UISearchBarDelegate, UITableViewDataSource, UITableViewDelegate, NSFetchedResultsControllerDelegate {
#available(iOS 2.0, *)
//Create fetchedResultsController to handle Inventory Core Data Operations
lazy var fetchedResultsController: NSFetchedResultsController<Inventory> = {
return self.setFetchedResultsController()
}()
//Reference to search text for filtering
var m_searchText = ""
func setFetchedResultsController() -> NSFetchedResultsController<Inventory>{
let moc = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let inventoryFetchRequest : NSFetchRequest<Inventory> = Inventory.fetchRequest()
var primarySortDescriptor = NSSortDescriptor(key: "name", ascending: true)//by default assume name.
print("primarySortDescriptor...")
if(g_appSettings[0].indextype=="numberfront"){
primarySortDescriptor = NSSortDescriptor(key: "barcode", ascending: true)
}else if(g_appSettings[0].indextype=="numberback"){
primarySortDescriptor = NSSortDescriptor(key: "barcodeReverse", ascending: true)
}else if(g_appSettings[0].indextype=="numberfourth"){
primarySortDescriptor = NSSortDescriptor(key: "barcodeFourth", ascending: true, selector: #selector(NSString.localizedCompare(_:)))
}
print("set primarySortDescriptor")
//let secondarySortDescriptor = NSSortDescriptor(key: "barcode", ascending: true)
inventoryFetchRequest.sortDescriptors = [primarySortDescriptor]
print("set sort descriptors to fetch request")
var storefilter : Store? = nil
var predicate: NSPredicate
//Store should never be set to nil, the first store should always be selected by default. For fringe cases just in case ... support added so doesn't break
if(g_appSettings[0].selectedStore != nil){
storefilter = g_appSettings[0].selectedStore
predicate = NSPredicate(format: "store = %#", storefilter!) //default predicate assuming store is selected
//However if search text is present then modify predicate
if(m_searchText != ""){
predicate = NSPredicate(format: "store = %# AND name contains[cd] %# OR store = %# AND barcode contains[cd] %#", storefilter!,m_searchText,storefilter!,m_searchText)
}
//This will ensure correct data relating to store is showing (and if any filters present, them as well)
inventoryFetchRequest.predicate = predicate
}else{
if(m_searchText != ""){
predicate = NSPredicate(format: "name contains[cd] %# OR barcode contains[cd] %#",m_searchText,m_searchText)
inventoryFetchRequest.predicate = predicate
//This will ensure correct data relating to store is showing
}
}
//default assume letter section
var frc = NSFetchedResultsController(
fetchRequest: inventoryFetchRequest,
managedObjectContext: moc,
sectionNameKeyPath: "lettersection",
cacheName: nil)
if(g_appSettings[0].indextype=="numberfront"){
frc = NSFetchedResultsController(
fetchRequest: inventoryFetchRequest,
managedObjectContext: moc,
sectionNameKeyPath: "numbersection",
cacheName: nil)
}else if(g_appSettings[0].indextype=="numberback"){
frc = NSFetchedResultsController(
fetchRequest: inventoryFetchRequest,
managedObjectContext: moc,
sectionNameKeyPath: "numberendsection",
cacheName: nil)
}else if(g_appSettings[0].indextype=="numberfourth"){
frc = NSFetchedResultsController(
fetchRequest: inventoryFetchRequest,
managedObjectContext: moc,
sectionNameKeyPath: "numberfourthsection",
cacheName: nil)
}
print("set the frc")
frc.delegate = self
return frc
}
#IBOutlet weak var searchBar: UISearchBar!
#IBOutlet weak var inventoryTable: UITableView!
// Start DEMO Related Code
var numberIndex = ["0","1","2","3","4","5","6","7","8","9"]
var letterIndex = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"]
var previousNumber = -1 //used so we show A,A, B,B, C,C etc for proper testing of sections
func createInventoryDummyData(number: Int) -> Inventory{
let moc = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let tempInventory = NSEntityDescription.insertNewObject(forEntityName: "Inventory", into: moc) as! Inventory
if(number-1 == previousNumber){
tempInventory.name = "\(letterIndex[number-2])-Test Item # \(number)"
previousNumber = -1//reset it again
}else{
tempInventory.name = "\(letterIndex[number-1])-Test Item # \(number)"
previousNumber = number //set previous letter accordingly
}
tempInventory.barcode = "00000\(number+1)00\(number)"
//special exception to demo barcode reader
if(number==5){
tempInventory.barcode = "0051111407592"
}
if(number==6){
tempInventory.barcode = "0036000291452"
}
tempInventory.barcodeReverse = String(tempInventory.barcode!.characters.reversed())
//Convert barcode into array of characters and take note if its size for indexing
let bcArraySize = Int(tempInventory.barcode!.characters.count) - 1//for correct indexing
var bcArray = tempInventory.barcode!.characters.map { String($0) }
print(bcArray)
print(bcArraySize)
//Take the digits from the 4th one at a time and convert to strings concatenating as you go.
let fourth = "\(bcArray[bcArraySize-3])"+"\(bcArray[bcArraySize-2])"+"\(bcArray[bcArraySize-1])"+"\(bcArray[bcArraySize])"
print(fourth)
//Finally convert that into a number again and set to barcodeFourth
tempInventory.barcodeFourth = fourth
print(tempInventory.barcodeFourth!)
//tempInventory.barcodeFourth =
//print(tempInventory.barcodeReverse)
tempInventory.currentCount = 0
tempInventory.id = number as NSNumber?
tempInventory.imageLargePath = "http://distribution.tech//uploads/inventory/7d3fe5bfad38a3545e80c73c1453e380.png"
tempInventory.imageSmallPath = "http://distribution.tech//uploads/inventory/7d3fe5bfad38a3545e80c73c1453e380.png"
tempInventory.addCount = 0
tempInventory.negativeCount = 0
tempInventory.newCount = 0
tempInventory.store_id = 1 //belongs to same store for now
//Select a random store to belong to 0 through 2 since array starts at 0
let lo = 0;
let hi = 2;
let aRandomInt = Int.random(range:lo...hi)
tempInventory.setValue(g_storeList[aRandomInt], forKey: "store") //assigns inventory to one of the stores we created.
return tempInventory
}
func createStoreDummyData(number:Int) -> Store{
let moc = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let tempStore = NSEntityDescription.insertNewObject(forEntityName: "Store", into: moc) as! Store
tempStore.address = "100\(number) lane, Miami, FL"
tempStore.email = "store\(number)#centraltire.com"
tempStore.id = number as NSNumber?
tempStore.lat = 1.00000007
tempStore.lng = 1.00000008
tempStore.name = "Store #\(number)"
tempStore.phone = "123000000\(number)"
return tempStore
}
// End DEMO Related Code
override func viewDidLoad() {
super.viewDidLoad()
let moc = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
print("InventoryController -> ViewDidLoad -> ... starting inits")
// // Do any additional setup after loading the view, typically from a nib.
// print("InventoryController -> ViewDidLoad -> ... starting inits")
//
//First check to see if we have entities already. There MUST be entities, even if its DEMO data.
let inventoryFetchRequest = NSFetchRequest<Inventory>(entityName: "Inventory")
//let storeFetchRequest = NSFetchRequest(entityName: "Store")
do {
let inventoryRecords = try moc.fetch(inventoryFetchRequest)
//Maybe sort descriptor here? But how to organize into sectioned array?
if(inventoryRecords.count<=0){
g_demoMode = true
print("No entities found for inventory. Demo mode = True. Creating default entities & store...")
//Reset the Stores
g_storeList = [Store]()
var store : Store //define variable as Store type
for index in 1...3 {
store = createStoreDummyData(number: index)
g_storeList.append(store)
}
//save changes for inventory we added
do {
try moc.save()
print("saved to entity")
}catch{
fatalError("Failure to save context: \(error)")
}
var entity : Inventory //define variable as Inventory type
for index in 1...52 {
let indexFloat = Float(index/2)+1
let realIndex = Int(round(indexFloat))
entity = createInventoryDummyData(number: realIndex)
g_inventoryItems.append(entity)
}
//Save the changes
(UIApplication.shared.delegate as! AppDelegate).saveContext()
print("finished creating entities")
}
}catch{
fatalError("bad things happened \(error)")
}
// //perform fetch we need to do.
// do {
// try fetchedResultsController.performFetch()
// } catch {
// print("An error occurred")
// }
print("InventoryController -> viewDidload -> ... finished inits!")
}
override func viewWillAppear(_ animated: Bool) {
print("view appearing")
//When the view appears its important that the table is updated.
//Trigger Event on SearchBar in case returning from BarCode Scanner
// self.searchBar:SearchBar textDidChange:recentlySearchedWord;
//searchBar.performSelector(":textDidChange")
//Perform another fetch again to get correct data~
do {
//fetchedResultsController. //this will force setter code to run again.
print("attempting fetch again, reset to use lazy init")
fetchedResultsController = setFetchedResultsController() //sets it again so its correct.
try fetchedResultsController.performFetch()
} catch {
print("An error occurred")
}
inventoryTable.reloadData()//this is important to update correctly for changes that might have been made
}
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
print("inventoryItemControllerPrepareForSegueCalled")
if segue.identifier == "inventoryInfoSegue" {
let vc = segue.destination as! InventoryItemController
vc.hidesBottomBarWhenPushed = true //hide the tab bar. This prevents crashing error from being on this page then syncing & returning.
if let cell = sender as? InventoryTableViewCell{
vc.inventoryItem = cell.inventoryItem //sets the inventory item accordingly, passing its reference along.
}else{
print("sender was something else")
}
}
}
// func tableView(tableView: UITableView, sectionForSectionIndexTitle title: String, atIndex index: Int) -> Int {
// //This scrolls to correct section based on title of what was pressed.
// return letterIndex.indexOf(title)!
// }
func sectionIndexTitles(for tableView: UITableView) -> [String]? {
//This is smart and takes the first letter of known sections to create the Index Titles
return self.fetchedResultsController.sectionIndexTitles
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let sections = fetchedResultsController.sections {
let currentSection = sections[section]
return currentSection.numberOfObjects
}
return 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "InventoryTableCell", for: indexPath as IndexPath) as! InventoryTableViewCell
print("IndexPath=")
print(indexPath)
let inventory : Inventory = fetchedResultsController.object(at: indexPath as IndexPath)
cell.inventoryItem = inventory
cell.drawCell() //uses passed inventoryItem to draw it's self accordingly.
return cell
}
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
if let sections = fetchedResultsController.sections {
let currentSection = sections[section]
return currentSection.name
}
return nil
}
func numberOfSections(in tableView: UITableView) -> Int {
if let sections = fetchedResultsController.sections {
return sections.count
}
return 0
}
func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
//dispatch_async(dispatch_get_main_queue()) {
//[unowned self] in
print("didSelectRowAtIndexPath")//does not recognize first time pressed item for some reason?
let selectedCell = self.tableView(tableView, cellForRowAt: indexPath) as? InventoryTableViewCell
self.performSegue(withIdentifier: "inventoryInfoSegue", sender: selectedCell)
//}
}
#IBAction func BarcodeScanBarItemAction(sender: UIBarButtonItem) {
print("test of baritem")
}
#IBAction func SetStoreBarItemAction(sender: UIBarButtonItem) {
print("change store interface")
}
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
self.barcodeTextDidChange(searchText: searchText)
}
func barcodeTextDidChange(searchText: String){
print("text is changing")
//Code to change NSFetchRequest Here~ & Reload Table
m_searchText = searchText //sets the local variable to this class so the setFetchedResultsController() will update accordingly
//Perform another fetch again to get correct data~
do {
//fetchedResultsController. //this will force setter code to run again.
print("attempting fetch again, reset to use lazy init")
fetchedResultsController = setFetchedResultsController() //sets it again so its correct.
try fetchedResultsController.performFetch()
} catch {
print("An error occurred")
}
inventoryTable.reloadData()//refreshes the data~
}
func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
print("ended by cancel")
searchBar.text = ""
m_searchText = "" //set the search text accordingly back to nothing.
//Perform another fetch again to get correct data~
do {
//fetchedResultsController. //this will force setter code to run again.
print("attempting fetch again, reset to use lazy init")
fetchedResultsController = setFetchedResultsController() //sets it again so its correct.
try fetchedResultsController.performFetch()
} catch {
print("An error occurred")
}
inventoryTable.reloadData()//refreshes the data~
searchBar.resignFirstResponder()
}
func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
print("ended by search")
searchBar.resignFirstResponder()
}
func searchBarTextDidEndEditing(_ searchBar: UISearchBar) {
print("ended by end editing")
searchBar.resignFirstResponder()
}
func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
print("DidBeginEditing")
//searchBar.keyboardType = UIKeyboardType.NamePhonePad
}
#IBAction func unwindBackToInventory(segue: UIStoryboardSegue) {
print("unwind attempt")
let barcode = (segue.source as? ScannerViewController)?.barcode
searchBar.text = barcode!
barcodeTextDidChange(searchText: searchBar.text!)//force it to re-run function manually.
print("barcode="+barcode!)
inventoryTable.reloadData()//reload the data to be safe.
}
}
//Extention to INT to create random number in range.
extension Int
{
static func random(range: ClosedRange<Int> ) -> Int
{
var offset = 0
if range.lowerBound < 0 // allow negative ranges
{
offset = abs(range.lowerBound)
}
let mini = UInt32(range.lowerBound + offset)
let maxi = UInt32(range.upperBound + offset)
return Int(mini + arc4random_uniform(maxi - mini)) - offset
}
}
globals.swift
import Foundation
import CoreData
//Array of Inventory & Store Core Data Managed Objects
var g_inventoryItems = [Inventory]()
var g_storeList = [Store]()
var g_appSettings = [AppSettings]()
var g_demoMode = false
Inventory+CoreDataProperties.swift
import Foundation
import CoreData
extension Inventory {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Inventory> {
return NSFetchRequest<Inventory>(entityName: "Inventory");
}
#NSManaged var addCount: NSNumber?
#NSManaged var barcode: String?
#NSManaged var barcodeReverse: String?
#NSManaged var barcodeFourth: String?
#NSManaged var currentCount: NSNumber?
#NSManaged var id: NSNumber?
#NSManaged var imageLargePath: String?
#NSManaged var imageSmallPath: String?
#NSManaged var name: String?
#NSManaged var negativeCount: NSNumber?
#NSManaged var newCount: NSNumber?
#NSManaged var store_id: NSNumber?
#NSManaged var store: Store?
//This is used for A,B,C ordering...
var lettersection: String {
let characters = name!.characters.map { String($0) }
return (characters.first?.uppercased())!
}
//This is used for 1,2,3 ordering... (using front of barcode and using barcodeReverse)
var numbersection: String {
let characters = barcode!.characters.map { String($0) }
return (characters.first?.uppercased())!
}
//This is used for 0000000123 ordering...(uses back number of barcode)
var numberendsection: String {
let characters = barcodeReverse!.characters.map { String($0) }
return (characters.first?.uppercased())!
}
//This is used for 0000000 -> 0123 ordering...(uses back 4th number of barcode)
var numberfourthsection: String {
let characters = barcodeFourth!.characters.map { String($0) }
//print("characters")
//print(characters)
return (characters.first?.uppercased())!
}
}
Inventory.Swift
import Foundation
import CoreData
class Inventory: NSManagedObject {
// Insert code here to add functionality to your managed object subclass
}
Screenshots of Errors
I have reviewed your all comments and contents posted here.
You have not shared one file here, but the problem is occurring you are creating invalid managed objects in the context.
And then whenever you call viewWillAppear() function in InventoryViewController, it saves the context.
Finally, it synced empty records into your database.
During parsing those invalid objects, it tried to parse nil value, so crashed.
Please never set default value for managed objects you are defining as properties.
I hope this will clarify your issue.
I was running into similar issue and i moved to the new CoreData api introduced in ios10.
This uses the NSPersistentContainer class to create the stack and create associated contexts.
This eliminates the need to manually call save or order the creation of fetch results controller.
Good blog post to read: https://useyourloaf.com/blog/easier-core-data-setup-with-persistent-containers/
My setup is a follows
create a store NSPersistentContainer
let persistentContainer = NSPersistentContainer(name: "ModelFileName");
configure settings
let url = NSPersistentContainer.defaultDirectoryURL()
let path = url.appendingPathComponent(persistentContainer.name);
description.shouldAddStoreAsynchronously = true; //write to disk should happen on background thread
self.persistentContainer.persistentStoreDescriptions = [description];
load the store
persistentContainer.loadPersistentStores(completionHandler: { (storeDescription, error) in
if let error = error {
fatalError("Unresolved error \(error), \(error.localizedDescription)")
}
//configure context for main view to automatically merge changes
persistentContainer.viewContext.automaticallyMergesChangesFromParent = true;
});
in the view controller you can access the view context by calling
persistentContainer.viewContext
if you need to make changes you can call
persistentContainer.performBackgroundTask({ (context) in ... });
or you can get a background context
let context = persistentContainer.newBackgroundContext()
context.perform({ ... })
In case this helps anyone else who gets the "API Misuse: Attempt to serialize store access on non-owning coordinator" error - I was getting the error because I accessed an object in a singleton that had not been destroyed and was still using the old NSManagedObjectContext after I reset the NSPersistentStore and NSManagedObjectContext.