How can a tableview (in another view controller) read this data from first view controller?
Should I put this into array or something? This is code for retrieving saved data, I already managed to save data.
do {
let request = NSFetchRequest(entityName: "Users")
let results = try context.executeFetchRequest(request)
if results.count > 0 {
for item in results as! [NSManagedObject] {
let name = item.valueForKey("username")
let password = item.valueForKey("passwords")
print(name!, password!)
array.append (name, password) // this do not work, can't put that in array so tableview can read array in another vc.
}
}
}
When I put name and password objects in array it says:
Cannot convert any object to array string
How can I retrieve core data to array so tableview can read from array, or should it read from coredata directly?
If you want to share data from VC A to VC B, you should use segue method and the display data in the tableView.
Segue method
self.performSegue(withIdentifier: "identifier", sender: nil)
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "identifier" {
let destination = segue.destination as! AlreadyStartViewController
destination.variable = variable /*and other*/
}
}
And then display data in the tableView
If you want to ask me about code - ask
Related
I keep getting a fatal error saying how a value was unwrapped and it was nil and I don't understand how. When I instantiate a view controller with specific variables they all show up, but when I perform a segue to the exact VC, the values don't show up.
Take these functions for example...
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
if let displayVC = storyboard?.instantiateViewController(withIdentifier: Constants.Storyboards.TeachStoryboardID) as? SchoolEventDetailsViewController {
displayVC.selectedEventName = events[indexPath.row].eventName
displayVC.selectedEventDate = documentsDate[indexPath.row].eventDate
displayVC.selectedEventCost = documentsCost[indexPath.row].eventCost
displayVC.selectedEventGrade = documentsGrade[indexPath.row].eventGrade
displayVC.selectedEventDocID = documentsID[indexPath.row]?.docID
navigationController?.pushViewController(displayVC, animated: true)
}
}
This combined with this function :
func verifyInstantiation() {
if let dateToLoad = selectedEventDate {
dateEditableTextF.text = dateToLoad
}
if let costToLoad = selectedEventCost {
costEditableTextF.text = costToLoad
}
if let gradesToLoad = selectedEventGrade {
gradesEditableTextF.text = gradesToLoad
}
if let docIDtoLoad = selectedEventDocID {
docIDUneditableTextF.text = docIDtoLoad
}
if let eventNameToLoad = selectedEventName {
eventNameEditableTextF.text = eventNameToLoad
}
}
Helps load the data perfectly, but when I try to perform a segue from a search controller the data is not there.
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.title = selectedEventName
I set the title of the vc to have the event name , and I also recently added a text field to store it as well for experimental purposes (this question).
Now the issue is I want to do a data transfer from an Algolia Search Controller to that VC and I got all the other fields to show up, except for one and that was the document ID. So I created a completion handler function to get the document ID as a string and have it inserted into the vc when the segue is performed, just like how it's there when the vc is instantiated.
Here is the function :
func getTheEventDocID(completion: #escaping ((String?) -> ())) {
documentListener = db.collection(Constants.Firebase.schoolCollectionName).whereField("event_name", isEqualTo: selectedEventName ?? navigationItem.title).addSnapshotListener(includeMetadataChanges: true) { (querySnapshot, error) in
if let error = error {
print("There was an error fetching the documents: \(error)")
} else {
self.documentsID = querySnapshot!.documents.map { document in
return EventDocID(docID: (document.documentID) as! String)
}
let fixedID = "\(self.documentsID)"
let substrings = fixedID.dropFirst(22).dropLast(3)
let realString = String(substrings)
completion(realString)
}
}
}
I thought either selectedEventName or navigationItem.title would get the job done and provide the value when I used the function in the data transfer function which I will show now :
//MARK: - Data Transfer From Algolia Search to School Event Details
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
otherVC.getTheEventDocID { (eventdocid) in
if let id = eventdocid {
if segue.identifier == Constants.Segues.fromSearchToSchoolEventDetails {
let vc = segue.destination as! SchoolEventDetailsViewController
vc.selectedEventName = self.nameTheEvent
vc.selectedEventDate = self.dateTheEvent
vc.selectedEventCost = self.costTheEvent
vc.selectedEventGrade = self.gradeTheEvent
vc.selectedEventDocID = id
}
}
}
}
But it ends up showing nothing when a search result is clicked which is pretty upsetting, I can't understand why they're both empty values when I declared them in the SchoolEventDetailsVC. I tried to force unwrap selectedEventName and it crashes saying there's a nil value and I can't figure out why. There's actually a lot more to the question but I just tried to keep it short so people will actually attempt to read it and help since nobody ever reads the questions I post, so yeah thanks in advance.
I'm a litte confused what the otherVC is, which sets a property of itself in the getTheEventDocID, whilste in the closure you set the properties of self, which is a different controller. But never mind, I hope you know what you are doing.
Since getTheEventDocID runs asynchronously, the view will be loaded and displayed before the data is available. Therefore, viewDidLoad does not see the actual data, but something that soon will be outdated.
So, you need to inform the details view controller that new data is available, and refresh it's user interface. Something like
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
otherVC.getTheEventDocID { (eventdocid) in
if let id = eventdocid {
if segue.identifier == Constants.Segues.fromSearchToSchoolEventDetails {
let vc = segue.destination as! SchoolEventDetailsViewController
vc.selectedEventName = self.nameTheEvent
vc.selectedEventDate = self.dateTheEvent
vc.selectedEventCost = self.costTheEvent
vc.selectedEventGrade = self.gradeTheEvent
vc.selectedEventDocID = id
vc.updateUI()
}
}
}
}
and in the destination view controller:
class SchoolEventDetailsViewController ... {
override func viewDidLoad() {
super.viewDidLoad()
updateUI()
}
func updateUI () {
navigationItem.title = selectedEventName
// and so on
}
}
Ok so I decided to attempt a workaround and completely ditched the getTheEventDocID() method because it was just causing me stress. So I decided to ditch Firebase generated document IDS and just use 10 digit generated ids from a function I made. I also figured out how to add that exact same 10 digit id in the Algolia record by just storing the random 10 digit id in a variable and using it in both places. So now instead of using a query call to grab a Firebase generated document ID and have my app crash everytime I click a search result, I basically edited the Struct of the Algolia record and just added an eventDocID property that can be used with hits.hitSource(at: indexPath.row).eventDocID.
And now the same way I added the other fields to the vc by segue data transfer, I can now do the same thing with my document ID because everything is matching :).
I have a UICollectionView that is populated by an array of productItem structs, the struct blueprint is in it's own swift file called ProductoItem.swift
struct ProductoItem {
let id: Int
let name: String
var price: String
var picture: String
var description: String
}
This works and I can successfully populate my UICollectionView with it, what I want to do now is to pass this struct to a detailView so I create this variable in the detailView.
var productos = [ProductoItem]()
And I put the following code in my prepareForSegue Method.
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "detalleProducto" {
let controller = segue.destination as! ProductoDetailViewController
controller.productos = productos
}
}
What I don't know how to do know is:
First as we are sending the entire array of structs I want to pass the values stored on the CollectionView cell's index to the DetailView to populate it using just the data of the product's cell, then I also want to have two buttons to go to the next / prev product that just go to the next / prev index value of my struct. How can I do this?
First, create a new 'currentIndex: Int' attribute in your detailView.
From your first UIViewController (the one that has the UICollectionView), pass the current index and the array to your DetailView:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "detalleProducto" {
let controller = segue.destination as! ProductoDetailViewController
controller.productos = productos
// do whatever you need to get your index
controller.currentIndex = self.collectionView.indexPathsForSelectedItems()[0].row
}
}
Then in your DetailView, you have your array and the current index, so you can just get the info of this specific product by doing:
let currentProduct = self.productos[currentIndex]
To get to the previous or next one, you can just increment or decrement 'currentIndex'.
I have been chasing this for two days but yet I am still not sure why my variable isn't being passed in my segue from my login view controller to the chat view controller via the navigation view controller.
I have a button that queries Firebase, checks if the user exists and returns a Firebase query reference for the user. I then want to pass this Firebase query reference when it finishes to the navigation controller's top view controller for use.
Inside my IBAction login button, I have:
var tempUserRef: FIRDatabaseReference?
channelRef.queryOrdered(byChild: "uid").queryEqual(toValue: uid).observeSingleEvent(of: .value, with: { (snapshot) in
if snapshot.exists() {
print("uid exist with \(snapshot.childrenCount) number of children")
for s in snapshot.children.allObjects as! [FIRDataSnapshot] {
tempUserRef = self.channelRef.child(s.key)
}
} else {
print("uid didn't exist")
if let name = self.nameField?.text { // 1
tempUserRef = self.channelRef.childByAutoId()
let channelItem = [
"name": name,
"uid": self.uid
]
tempUserRef?.setValue(channelItem)
}
}
self.userRef = tempUserRef
DispatchQueue.main.async {
self.performSegue(withIdentifier: "LoginToChat", sender: tempUserRef)
print("passsed \(self.userRef)")
}
})
Here is my segue:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if "LoginToChat" == segue.identifier {
if let navVc = segue.destination as? UINavigationController {
if let chatVc = navVc.topViewController as? ChatViewController {
chatVc.senderDisplayName = nameField?.text
if let userRef = sender as? FIRDatabaseReference {
chatVc.userRef = userRef
print("passsing \(self.userRef) to \(chatVc)")
}
}
}
}
super.prepare(for: segue, sender: sender)
}
The print statements all look good on my login controller but when I get to the chat view controller, the userRef is still nil. So my sense is that I have the right segue inputs and handoffs but that the async nature of the data is somehow out of step with my segue.
The chat view controller is using the JSQMessages library if that makes a difference.
Thanks for your help.
EDIT:
Based off feedback I've moved the super.prepare but userRef is still not being set consistently.
SECOND EDIT:
Following paulvs' suggestion, I removed my button segue. However, I did have to create another segue that connected view controller to view controller like this SO question.
Place the call to super.prepare at the end of the function. Otherwise, the segue is performed before you set your variables.
I have dynamic tableview, wherein one of the cell (duration) when tapped opens another view controller which is a list of duration viz (30 min, 1 hour, 2 hours and so fort). One of the durations when selected should display the selected duration in the first view controller. I am able to pass the data back to first view controller using unwind segue but unable to display the passed value. DOn't know whats missing.
I am displaying the code below:
FIRST VIEW CONTROLLER (CALLING)
#IBAction func unwindWithSelectedDuration(segue:UIStoryboardSegue) {
var cell = tableView.dequeueReusableCellWithIdentifier("durationCell") as! durationTableViewCell
if let durationTableViewController = segue.sourceViewController as? DurationTableViewController,
selectedDuration = durationTableViewController.selectedDuration {
cell.meetingDurationCell.text = selectedDuration
duration = selectedDuration
}
SECOND VIEW CONTROLLER (CALLED)
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "SaveSelectedDuration" {
if let cell = sender as? UITableViewCell {
let indexPath = tableView.indexPathForCell(cell)
if let index = indexPath?.row {
selectedDuration = durationList[index]
}
}
}
}
tableView.dequeueReusableCellWithIdentifier should only be called within tableView:cellForRowAtIndexPath:. It has no use outside this context.
The easiest fix is to just reload the table once you have stored the selected duration:
#IBAction func unwindWithSelectedDuration(segue:UIStoryboardSegue) {
if let durationTableViewController = segue.sourceViewController as? DurationTableViewController {
selectedDuration = durationTableViewController.selectedDuration
tableView.reloadData()
}
}
Note that this assumes you only need one selectedDuration for your whole table, rather than one per row. If you need one per row, I assume you have them stored in an array somewhere, so it is that array that should be updated instead before the reloadData.
I am attempting to query for data from a Parse table to add it to a prepareForSegue function. But once I go into the newViewController the label is blank. Here's my line of code.
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "marathonDetail"){
var upcoming: marathonDetailViewController = segue.destinationViewController as! marathonDetailViewController
let indexPath = self.marathonsTableView.indexPathForSelectedRow!
let currentCell = marathonsTableView.cellForRowAtIndexPath(indexPath) as! marathonTableViewCell
let marathonEvents = currentCell.marathonName.text
upcoming.nameMarathon = marathonEvents
self.marathonsTableView.deselectRowAtIndexPath(indexPath, animated: true)
var query = PFQuery(className: "marathons")
query.whereKey("marathonName", equalTo: marathonEvents!)
query.findObjectsInBackgroundWithBlock{
(marathonPickeds: [PFObject]?, error: NSError?) -> Void in
if (error == nil){
if let marathonPicked = marathonPickeds as? [PFObject]?{
for marathonPicked in marathonPickeds!{
var selectedDescription = marathonPicked.description
upcoming.marathonDescription = selectedDescription
print(selectedDescription)
}
}
}else {
print(error)
}
}
}
}
The marathonsEvents= currentCell.marathonName.text works well but the marathonDescription is blank.
Any advice? I am using Parse as my backend XCODE 7, and swift
You're performing a network call on a background thread so by the time its finished you've already completed the segue. What you probably want to do is:
Pull that query logic out into a separate class, get it out of your view controllers.
In this instance perform the request in the view controller that is being pushed to. You can start it in viewWillAppear and refresh your view when its finished. It looks like it has all the information it needs to perform the request using just the marathonEvents.