I have a collectionView controller with a collectionView populated by a database. In this controller I have reloadData() in 'viewDidAppear' and 'viewWillAppear' functions.
The collectionView controller has a modal segue to a gameViewController. After the 'game' is finished in the gameViewController, the database is updated (this works) and the modal is dismissed back to the collectionView controller.
func gameOver() {
self.dismissViewControllerAnimated(true, completion: nil)
}
However despite 'viewDidAppear' and 'viewWillAppear' being called (I confirm this with a println()) when the gameViewController is dismissed, the collectionView data does not reload. So the updated database data isn't shown in the collectionView.
The collectionView data does reload if I dismiss the collectionView controller, and then reopen it.
How do I ensure the collectionView controller - reloadData() - is called after dismissing the gameViewController?
Code:
class GameViewController: UIViewController {
var collectionView: LevelsCollectionViewController!
override func viewDidLoad() {
super.viewDidLoad()
// code not related to question - creates game scene
}
override func viewDidDisappear(animated: Bool) {
collectionView.reloadData()
}
func gameOver() {
self.dismissViewControllerAnimated(true, completion: nil)
}
class LevelsCollectionViewController: UICollectionViewController {
// code setting up cells
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
println("viewWillAppear")
self.collectionView!.reloadData()
self.collectionView!.setNeedsDisplay()
}
override func viewDidAppear(animated: Bool) {
super.viewWillAppear(animated)
println("viewDidAppear")
self.collectionView!.reloadData()
self.collectionView!.setNeedsDisplay()
}
}
UPDATE:
The println() viewWillAppear & viewDidAppear are printed in the console after the dismissViewController, but the collectonView data isn't reloaded.
The database that the collectionView is taken from is updated (done is another function called before gameOver().
I tried the method suggested below of having a reference to UIViewController and calling reloadData on that from viewDidDisappear, but nothing happens.
Actually that's what the completion argument is for
func gameOver() {
self.dismissViewControllerAnimated(true) { () -> Void in
self.collectionView.reloadData()
}
}
Check to make sure that your data source is being updated (a few println's in your viewDidAppear() will help) - in addition, try storing a reference to the collectionView controller and calling reloadData() on it in the viewWillDisappear() method of your gameViewController.
Some days I want to kick my own backside!
I 'stupidly' forgot to reload the temp array (levelProgress) that was holding the information taken from the database (held on array in appDelegate) in the collectionViewController.
Thus while the database and the array in appDelegate were being updated, the reloadData() was still working off the tempArray in the collectionViewController. Resetting this tempArray on viewDidAppear(), then reloadData() did the trick.
override func viewDidAppear(animated: Bool) {
super.viewWillAppear(animated)
levelProgress = appDelegate.levelProgress
self.collectionView!.reloadData()
self.collectionView!.setNeedsDisplay()
}
Think I'm going code blind
Related
i am calling a GET(method) API on viewDidAppear function of a view controller. i am presenting a new view controller using navigation controller over my first view controller. on the second view controller i am calling an API of Post Method to add another entry into my previous screen Get method API. But when I dismiss the second View Controller the Get API data remains the same and when i again runs the code the data was updated on the first view controller. Can someone tell me that how to check on first view controller that my second view controller is dismissed so that i can call API there.
I got the solution for this. It didn't work by calling the API on viewDidAppear() or viewWIllAppear() . This will be done by using swift closures.
Below is the code:
class 1stViewController: UIViewController {
#IBAction func buttonTapped(_ sender: UIButton) {
guard let secondViewController = self.storyboard?.instantiateViewController(withIdentifier: "SecondViewController") as? SecondViewController else { return }
secondController.callbackClosure = { [weak self] in
print("call API")
}
self.navigationController?.pushViewController(secondController, animated: true)
}
}
On Second view Controller:
class SecondViewController: UIViewController {
var callbackClosure: ((Void) -> Void)?
override func viewWillDisappear(_ animated: Bool) {
callbackClosure?()
}
}
If I have two ViewControllers one which contains a UITableView and another which updates data in the tableView. How would I reload the table data once I pop of the viewController and go back to the view with the tableView?
I already tried using viewDidAppear
You could use viewWillAppear just like Rajesh suggested:
override func viewWillAppear(_ animated: Bool) {
tableView.reloadData()
}
Or you could use a callback function to pass data and reload view controller 1's tableview.
In ViewController 2, define your callback function:
// Callback function
var callbackResult: ((data) -> ())?
And call it before going back to ViewController 1:
callbackResult?(data)
self.navigationController?.popViewController(animated: true)
In ViewController 1, use the callback function's closure to collect the result and reload your tableView. This can happen inside prepareForSegue, for example:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToViewController2" {
let destinationVC = segue.destination as! ViewController2
// Set any variable in ViewController2
destinationVC.callbackResult = { result in
// assign passing data etc..
self.tableView.reloadData()
}
}
}
You may try doing something like this:
class TableViewController: UITableViewController {
func showUpdatingViewController() {
let vc = UpdatingViewController()
vc.onUpdate = { [weak self] in
self?.tableView.reloadData()
}
navigationController?.pushViewController(vc, animated: true)
}
}
class UpdatingViewController: UIViewController {
var onUpdate: (() -> Void)?
func updatesFinished() {
onUpdate?()
dismiss(animated: true, completion: nil)
}
}
I was having similar issue and using viewWillAppear or viewDidAppear did not help me to reload the tableview.
I solved my situation by putting the reloadData() call within the unwindSegue
#IBAction func unwindToVCSetupDataScreen(_ unwindSegue: UIStoryboardSegue) {
/// Nothing is actually needed here
/// https://www.youtube.com/watch?v=WaSlHXNah7E #6:25
/// CTRL-Drag from Back button to the "exit" square at the very top of VC
tableView.reloadData()
}
Im using startApp to display ads but when the view disappears it doesn't show the ad. I have startAppAd = STAStartAppAd() in viewDidLoad() I'm not quite sure what is going wrong.
override func viewDidAppear(_ animated: Bool) {
startAppAd?.load()
}
override func viewDidDisappear(_ animated: Bool) {
super.viewDidDisappear(animated)
startAppAd?.show()
}
viewDidDisappear is called when the vc is about to dimiss or popped , so any property is in it's way to deallocate if that vc is not strongly linked , so move the show method also inside viewDidAppear or in the ad load finish callback if any
I've been looking at and trying all the solutions others have posted to this problem, but I'm still not getting it.
My use case is very simple. I have a viewController with a button, when that button is pressed I want to navigate to another tab and reload the data including an api call.
When using the button, I navigate to the tab fine, but viewDidAppear is not being called.
If on another tab, and navigate using the tab bar, viewDidAppear works fine. Also viewWillAppear is working, but I have to add a manual delay to the functions I want to call so it's not ideal.
So what do I need to do to navigate using self.tabBarController.selectedIndex = 0 and get the functionality of viewDidAppear?
Update: The viewWillAppear method I added gets called but I have to add a delay to my functions in order for them to work, and it's a bit clunky, not ideal. Not sure why viewDidAppear will not work :(
Here is a screenshot of the structure:
I appreciate any help on this one!
The "current" ViewController is my tab index 2:
import UIKit
class PostPreviewVC: UIViewController {
//Here I create a post object and post it to the timeline with the below button
#IBAction func postButtonPressed(_ sender: Any) {
//create the post via Firebase api
self.tabBarController?.selectedIndex = 0
}
}
In my destination viewController:
import UIKit
import Firebase
import SDWebImage
import AVFoundation
class HomeVC: UIViewController {
// MARK: - PROPERTIES
var posts = [Post]()
let refreshControl = UIRefreshControl()
//more properties...
#IBOutlet weak var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
setupUI()
configureTableView()
reloadTimeline()
UserFirebase.timeline { (posts) in
self.posts = posts
self.tableView.reloadData()
}
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
print("viewDidAppear")
_ = self.view
setupUI()
configureTableView()
reloadTimeline()
UserFirebase.timeline { (posts) in
self.posts = posts
self.tableView.reloadData()
}
}
override func viewWillAppear(_ animated: Bool) {
super.viewDidAppear(animated)
print("viewWillAppear")
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
self.reloadTimeline()
self.configureTableView()
}
}
//All the tableview code below here...
}
Added a custom class for my tab bar controller:
import UIKit
class TabBarController: UITabBarController, UITabBarControllerDelegate {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
print("viewDidAppear in tabBar custom Class called")
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
print("viewWillAppear in tabBar custom Class called")
}
}
When you are using UITabBarController, the method viewDidLoad will called only once when any UIViewController is loaded in memory. After that, when you are navigating the same UIViewController, then it will load from memory.
In order to overcome this problem, you must divide your code in viewDidLoad & viewDidAppear. So, in viewDidLoad, you only put that code which you want to intialize once throughout the app such as adding UIView's or other things, while in viewDidAppear / viewWillAppear, you can make API calls or some functions which fetches dynamic data.
Finally, when you are calling self.tabBarController.selectedIndex = 0, it will call viewDidLoad only once and viewDidAppear / viewWillAppear every time when you are navigating that UIViewController.
Hope this helps to understand like how UITabBarController works.
For UITabBarController viewDidLoad only gets called once. and your viewWillAppear and viewDidAppear get called multiple times. you can either check if your viewWillAppear gets called or not. because your view will appear gets called before your viewDidAppear it's just like going through the reverse engineering process.
You can also add viewDidAppear method into your UITabBarController custom class. and call its superclass method into it in that way I think it will solve your problem.
Note: In the case of UITabbarController, Always do your UI update task and API calling a task in either
viewWillAppear or viewDidAppear
i have a UITableview that has unique cells,
each cell has it's own class and they have actions that i want to connect to my main UITableviewcontroller
I attach a protocol and open it in the tableviewcontroller
but it doesn't get read
how could I initialise it or what am I doing wrong ?
here is my cell class :
import UIKit
class AddFaxHeadlineTableViewCell: UITableViewCell {
var delegate: AddFaxHeadlineProtocol?
#IBOutlet weak var addButton: UIButton!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
#IBAction func onAddFaxNumberPressed(_ sender: Any) {
delegate?.faxButtonPressed()
}
}
protocol AddFaxHeadlineProtocol{
func faxButtonPressed()
}
and in my tableviewcontroller I extend the protocol:
class SummaryMainTableViewController: UITableViewController, AddFaxHeadlineProtocol, AddEmailHeadlineProtocol {
but the function itself never gets read:
func faxButtonPressed() {
var indexToInsert = 0
for forIndex in 0..<sectionsData.count {
// render the tick mark each minute (60 times)
if (sectionsData[forIndex] == "addFaxHeadline") {
indexToInsert = forIndex + 1
}
}
sectionsData.insert("addNewFax", at: indexToInsert)
mainTableView.reloadData()
}
You need to call:
cell.delegate = self
In your cellForRowAtIndex method
This is the common mistake done in protocols and delegates to forget to call delegate.
Here are few examples you can check all have missing is calling delegate:-
Swift delegate beetween two VC without segue
Delegate seems to not be working, according to the console
How to present another view controller after dismiss from navigation controller in swift?
Another way to go inside the vc without protocols
let cell = ///
cell.addButton.tag = indexPath.row
cell.addButton.addTarget(self, action: #selector(buttonTapped(_:)), for: .touchUpInside)
}
#objc func buttonTapped(_ sender:UIButton) {
print(sender.tag)
}
Check that you are doing this:
cell.delegate = self (It's required)
Then improve your line of code like below. Because you will not set delegate then by calling this delegate method directly will get crashed.
#IBAction func onAddFaxNumberPressed(_ sender: Any) {
if let delegateObject = delegate {
delegateObject.faxButtonPressed()
}
}
Second,
In this line, delegateObject.faxButtonPressed(), you will need to send some parameter to identify that will cell is clicked. So you can pass here button tag or you can pass cell also.