I'm having an issue while using reload data to refresh my UITableView.
As a quick description:
This class received an NSNotification contain the object with data that need to added to the list and device must vibrate once that indicate that the data is received. The device itself vibrate but the list does not updated, so no new data is added to the list.
Code when notification is received:
dispatch_async(dispatch_get_main_queue(), {
let object = notification.object as! Attendee
self.handshakesArray.append(object)
self.tableViewMain.reloadData()
AudioServicesPlayAlertSound(UInt32(kSystemSoundID_Vibrate))
})
I don't know if this is an iOS issue or my implementation is wrong.
Edit:
class Shakes: UITableViewController {
private var handshakesArray = [Attendee]()
override func viewDidLoad() {
super.viewDidLoad()
}
func executeTask(notification:NSNotification) {
dispatch_async(dispatch_get_main_queue(), {
let object = notification.object as! Attendee
self.handshakesArray.append(object)
self.tableViewMain.reloadData()
AudioServicesPlayAlertSound(UInt32(kSystemSoundID_Vibrate))
})
}
// ........
}
Thanks in advance
I think you haven't initialized self.handshakesArray. Please initialise it by
var self.handshakesArray = [objectType]()
Make sure you are setting datasource and delegate for self.tableViewMain in you viewDidLoad func or from the storyboard .
self.tableViewMain.delegate = self
self.tableViewMain.dataSource = self
Related
I am new to Swift and Xcode, but I have been reading on here and watching videos on YouTube to guide me along with starting my app. I can't seem to get my button to save its state once the app is closed and re-opened. I used UserDefault To Save Button State as an example, but following it still did not get the button state saved.
I set the state with the Interface Builder and so far have the below code:
#IBAction func ownedButton(_ sender UIButton) {
sender.isSelected = !sender.isSelected
UserDefaults.standard.set(sender.isSelected, forKey: "isSaved")
UserDefaults.standard.synchronize()
}
Clicking the button will keep it selected until clicked again, so it is partially working. It looks like I need some code to in the viewDidLoad section, but I haven't been able to figure out what it should be.
Thank you for any help!
A habit from my Objective-C days is to write a wrapper around the properties in UserDefaults. This way, everything is compile-time checked and the use of strings as keys is minimized:
// Properties.swift
import Foundation
fileprivate var standardDefaults = UserDefaults.standard
class Properties {
static func registerDefaults() {
standardDefaults.register(defaults: [
kIsButton1Selected: false,
kIsButton2Selected: true
])
}
fileprivate static let kIsButton1Selected = "isButton1Selected"
static var isButton1Selected: Bool {
get { return standardDefaults.value(forKey: kIsButton1Selected) as! Bool }
set { standardDefaults.set(newValue, forKey: kIsButton1Selected) }
}
fileprivate static let kIsButton2Selected = "isButton2Selected"
static var isButton2Selected: Bool {
get { return standardDefaults.value(forKey: kIsButton2Selected) as! Bool }
set { standardDefaults.set(newValue, forKey: kIsButton2Selected) }
}
}
Then in your View Controller:
override func viewDidLoad() {
// Always call registerDefaults before you use UserDefaults
// for the first time in your app
Properties.registerDefaults()
button1.isSelected = Properties.isButton1Selected
button2.isSelected = Properties.isButton2Selected
}
#IBAction func ownedButton(_ sender: UIButton) {
sender.isSelected = !sender.isSelected
switch sender {
case button1:
Properties.isButton1Selected = sender.isSelected
case button2:
Properties.isButton2Selected = sender.isSelected
default:
break
}
}
You can replace the switch with key-value observing but remember to remove the KVO on deinit.
In my model i've got a function to read in data from firebase.
I call completionHandler(true) when that's done.
This is my viewDidLoad function in my controller that extends UITableViewController.
override func viewDidLoad()
{
super.viewDidLoad()
let activityIndicatorView = UIActivityIndicatorView(activityIndicatorStyle: UIActivityIndicatorViewStyle.whiteLarge)
tableView.backgroundView = activityIndicatorView
self.activityIndicatorView = activityIndicatorView
activityIndicatorView.startAnimating()
model.readInFirebaseData { (success) in
print("data read in")
activityIndicatorView.stopAnimating()
dataArray = model.firebaseDataArray
self.tableView.reloadData()
}
searchController.searchResultsUpdater = self
searchController.dimsBackgroundDuringPresentation = false
tableView.tableHeaderView = searchController.searchBar
}
But the table remains empty and for whatever reason self.tableView.reloadData() isn't populating the table as i'd like but if I segue from the TableViewController and come back the list is populated.
I can't see exactly where i'm going wrong.
Thanks.
Update:
I still couldn't get it working so instead of a completionHandler i used a delegate. What i did was:
Singleton:
protocol Refresh{
func refreshData()
}
var delegate:Refresh?
func readInFirebaseData()
{
self.ref.child("users").observe(DataEventType.childAdded, with: { (snapshot) in
user.name = value?["name"] as? String ?? ""
self.dict.updateValue(user, forKey: uid)
DispatchQueue.main.async {
self.delegate?.refreshData()
print("main thread dispatch")
}
})
}
The TableViewController:
class ListController: TableViewController, Refresh{
viewDidLoad()
{
model.delegate = self
}
func refreshData() {
print("called")
array = model.array
self.tableView.reloadData()
}
That all works. The only issue really that I don't know the answer to is the DispatchQueue.main.async is getting called everytime firebase reads in a "user". But I put it at the end of the readInFirebase function and nothing was populated on the list. But in any case it works at the moment.
Probably readInFirebaseData method is asynchronous and the callback runs on a thread different from the main one.
Remember that all the UIKit related calls must be run on the main thread.
Try with:
model.readInFirebaseData { (success) in
print("data read in")
dataArray = model.firebaseDataArray
DispatchQueue.main.async {
activityIndicatorView.stopAnimating()
self.tableView.reloadData()
}
}
Be sure to set delegate and dataSource:
tableView.delegate = self
tableView.dataSource = self
And make sure you call reloadData() from Main Thread:
DispatchQueue.main.async {
self.tableView.reloadData()
}
Calling it from background threads would typically not lead to your table reloaded, since this operation is UI-related. Any UI related operations should be performed from main thread.
I am new to swift and I am trying to make this note app. I have split view controller that goes in my first view controller and that view controller connects to a table view controller. Everything works perfectly is just that when I launch the app I have all the notes like I want but when I try to go back to my first view controller and come back to my table view controller, all the notes are duplicated every single time I do it. I tried everything I can try, is there anyone who can help me
my MasterViewController is
import UIKit
class MasterViewController: UITableViewController {
var detailViewController: DetailViewController? = nil
override func viewDidLoad()
{
super.viewDidLoad()
Note.loadNotes() // The problem is here, I think
noteTable = self.tableView
// Do any additional setup after loading the view, typically from a nib.
let addButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(insertNewObject(_:)))
navigationItem.rightBarButtonItem = addButton
if let split = splitViewController
{
let controllers = split.viewControllers
detailViewController = (controllers[controllers.count-1] as! UINavigationController).topViewController as? DetailViewController
}
}
My loadNotes function is
class func loadNotes()
{
let defaults:UserDefaults = UserDefaults.standard
let saveData: [NSDictionary]? = defaults.object(forKey: kAllNotes) as? [NSDictionary]
if let data:[NSDictionary] = saveData
{
for i:Int in 0 ..< data.count
{
let n:Note = Note()
n.setValuesForKeys(data[i] as! [String : Any])
allNotes.append(n)
}
}
}
Your loadNotes method keeps appending. The first line of loadNotes should be:
allNotes = [Note]()
Then it starts with an empty array and fills it up.
And why is loadNotes a static method? That's a bad design. Make Notes a normal class and make loadNotes an instance method.
On an unrelated note (no pun intended), do not use UserDefaults to store app data. Only use it to store little bits of information.
I have an app with UITableView, Core Data and NSFetchedResultsController as well. I have passed data to the DetailViewController. And I can delete them from the DetailViewController! In the Apple's iOS Notes app, you can see such as functions as I wanted! When you delete a notes from the DetailViewController ( for example ), object deleted and Notes app automaticlly shows the next or previos notes! I want to create such as function. How update user interface after deleted current object? Here's my codes! Thanks `
import UIKit
import CoreData
class DetailViewController: UIViewController {
#IBOutlet weak var containerLabel: UILabel!
var retrieveData:NSManagedObject!
var managedObjectContext:NSManagedObjectContext!
var manager:Manager!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
self.containerLabel.userInteractionEnabled = false
self.containerLabel.textColor = UIColor.redColor()
self.containerLabel.alpha = 0
UIView.animateWithDuration(2.5) { () -> Void in
self.containerLabel.alpha = 1
}
if let demo = self.retrieveData.valueForKey("titleField") as? String {
self.containerLabel.text = demo
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func backToMain(sender: AnyObject) {
// Back to the MainTableViewController
self.dismissViewControllerAnimated(true, completion: nil)
}
#IBAction func trashButton(sender: AnyObject) {
self.managedObjectContext.deleteObject(retrieveData)
do {
try self.managedObjectContext.save()
} catch {
}
self.dismissViewControllerAnimated(true, completion: nil)
}
`
If I have 5 items on the list like so:
When I select fourth item from the list ( for example ). And detailVC shows me selected item like this:
And I want to delete them. When I delete "Four" and then my containerLabel.text shows previous objects from the list. They're after "Four" is deleted, "Three","Two" and "One" as well. After "One" is deleted my containerLabel.text shows strings
But I have left single object called as "Five"
My problem is "Five"! I can't delete it. Example: In iOS Notes App, if you have five objects on the list like my demo app. When you select fourth object from the list ( for example ). And begin deleting them, after "Four" is delete iOS Notes App shows "Five". And "Five" ( last object on the list ) is deleted and then iOS Notes App shows "Three", "Two" and "One". Maybe problem line is here:
if index != 0 {
self.retrieveData = fetchedObject[index! - 1]
} else {
self.retrieveData == fetchedObject[0]
}
Let's take the easy (but not so elegant) route here. You'll have to pass over all the fetched objects to the detail VC like this:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "yourSegueIdentifier"{
if let destinationVC = segue.destinationViewController as? DetailViewController{
destinationVC.managedObjectContext = yourContext
destinationVC.retrieveData = yourManagedObject
destinationVC.arrayOfFetchedObjects = yourFetchedResultsController.fetchedObjects
//pass over other data...
}
}
}
Then, in your detailVC, write a method that will be executed when you press the delete button. Something like this:
#IBAction func trashButton(sender: AnyObject) {
//make sure you have an array with YourObjects
guard let fetchedObjects = arrayOfFetchedObjects as? [YourObjectType] else {return}
//get index of the shown object in the array of fetched objects
let indexOfObject = fetchedObjects.indexOf(retrieveData)
//delete the object from the context
self.managedObjectContext.deleteObject(retrieveData)
do {
try self.managedObjectContext.save()
//delete the object from the fetchedObjects array
fetchedObjects.removeAtIndex(indexOfObject)
} catch {
}
//get the object that should be shown after the delete
if indexOfObject != 0{
//we want the object that represents the 'older' note
retrieveData = fetchedObjects[indexOfObject - 1]
updateUserInterface(true)
}
else{
//the index was 0, so the deleted object was the oldest. The object that is the oldest after the delete now takes index 0, so just use this index. Also check for an empty array.
if fetchedObjects.isEmpty{
updateUserInterface(false)
}
else{
retrieveData = fetchedObjects[0]
updateUserInterface(true)
}
}
}
func updateUserInterface(note: Bool){
switch note{
case true:
//update the user interface
if let demo = retrieveData.valueForKey("titleField") as? String {
self.containerLabel.text = demo
}
case false:
self.containerLabel.text = "no more notes"
}
}
You either need to pass the details view controller
A list of all managed objects and an index for where in the list to start
A current managed object and a callback to get the next object
In order for it to have enough information to do what you want. The callback approach is nicest and is a simple form of delegate, where your master view controller is the delegate supplying the extra data.
So I am creating a fairly simple program using Realm as my database. I am fairly new to programing in Swift (or any OS X or iOS environment.) In my program when a button is pressed IBAction func createInvoice I want a few things to happen, I want to count the previous rows in the database and create an invoice number, I want to write new data to the database and I want to call a new view and view controller and pass along the invoice number. My code works except for one thing when using Realm the new view controller is called (override func prepareForSegue) before the invoice number is created so a 0 value is passed along to the new view controller.
If I create a dummy invoice number value such as let invoicenumber = 42 everything works perfectly. It seems that Realm is causing things to happen 'out of order' How can I make the veiwcontroller wait for a value before loading?
#IBAction func createInvoice(sender: AnyObject) {
let realm = Realm()
let invoicepull = Invoice()
let invoicecount = realm.objects(Invoice)
let invoicenraw = invoicecount.count
let a = 100
let invoicenumber = a + invoicenraw
var invoicefile = Invoice()
invoicefile.inumber = invoicenumber
invoicefile.cnumber = clientcombo.stringValue
invoicefile.cost = owed.doubleValue
invoicefile.paid = paid.doubleValue
invoicefile.sevicecode = service.stringValue
invoicefile.dateofservice = NSDate()
// Save your object
realm.beginWrite()
realm.add(invoicefile)
realm.commitWrite()
//Sent notification
performSegueWithIdentifier("cinvoiceseuge", sender: nil)
println("Inside Action")
println(invoicenumber)
dismissViewController(self)
}
override func prepareForSegue(segue: NSStoryboardSegue, sender: AnyObject!) {
if (segue.identifier == "cinvoiceseuge") {
//Checking identifier is crucial as there might be multiple
// segues attached to same view
var detailVC = segue.destinationController as! invociegenerator;
detailVC.toPass = invoicenumber
println("Inside Sugue")
println(invoicenumber)
}
}
If createInvoice is happening on a different thread than prepareForSegue, you'll have to refresh the realm (Realm().refresh()) before accessing your invoicenumber variable (which I assume is of type RealmSwift.Object).
I have solved this issue, thanks to the help of #Shmidt by using Realm's built in notification center. To use the notifications you can use this basic structure.
var notificationToken: NotificationToken?
deinit{
let realm = Realm()
if let notificationToken = notificationToken{
realm.removeNotification(notificationToken)
}
}
override func viewDidLoad() {
super.viewDidLoad()
let realm = Realm()
notificationToken = realm.addNotificationBlock { note, realm in
println("The realm is complete")
}
...
}
One small other error in my code was let invoicenumber = a + invoicenraw I needed to drop the let as it is a variable and not a constant.