On my iPad app, I have a UIViewController with a button that open a modalView.
#IBAction func showPostCommentViewController(sender: AnyObject){
let modalView = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("PostCommentViewController") as! PostCommentViewController
modalView.modalTransitionStyle = UIModalTransitionStyle.CoverVertical
modalView.modalPresentationStyle = UIModalPresentationStyle.FormSheet
modalView.delegate=self
self.presentViewController(modalView, animated: true, completion: nil)
}
When I close the modalView with dismissViewControllerAnimated, I would like "refresh" my view controller (because I added new content). But as the modal view is a "formsheet" style, viewDidAppear or viewWillAppear aren't called.
I tried to use setNeedsDisplay, but it doesn't work.
I don't know how to do.
This would be a perfect use case for the delegate pattern.
1) define a protocol within PostCommentViewController.
protocol PostCommentVCInformationDelegate {
func hasDismissedPostCommentViewController(controller:PostCommentViewController)
}
2) Set a delegate variable within PostCommentViewController
var delegate: PostCommentVCInformationDelegate?
3) When you dismiss PostCommentViewController, you will call delegate?.hasDismissedPostCommentViewController(self)
This will send information back to the presenting VC.
4) Now we have our presenting View Controller conform to this protocol.
class ViewController: UIViewController, PostCommentVCInformationDelegate
5) When presenting the modal View:
modalView.delegate = self
6) Finally, we implement:
func hasDismissedPostCommentViewController(controller: PostCommentViewController) {
//Update
}
Related
I am new in Programming and swift, and I have tried to read some solutions in stack overflow, but to be honest I don't really grasp with the answer :(
I have 2 view controllers. a homeVC and a LoginVC. homeVC is my initial view controller. in viewDidLoad I have firebase function that can check if the user has logged in before or not. if not, then the user will be send to loginVC. here is my simplified code in the HomeVC
import UIKit
import Firebase
class HomeVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// to check whether the user has already logged in or not
Auth.auth().addStateDidChangeListener { (auth, user) in
if user == nil {
let login = self.storyboard?.instantiateViewController(withIdentifier: "login") as! LoginVC
self.present(login, animated: true, completion: nil)
}
}
print("user enter homeVC")
}
}
and here is my loginVC
import UIKit
import Firebase
import GoogleSignIn
class LoginVC : UIViewController, GIDSignInUIDelegate {
#IBOutlet weak var googleButton: GIDSignInButton!
#IBOutlet weak var emailButton: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
// delegate declaration
GIDSignIn.sharedInstance().uiDelegate = self
}
#IBAction func googleButtonDidPressed(_ sender: Any) {
GIDSignIn.sharedInstance().signIn()
}
}
the app can perform as I expected. but there is a warning in my debugging area :
Warning: Attempt to present LoginVC: 0x7fc315714f40 on
HomeVC: 0x7fc3155095c0 whose view is not in the window
hierarchy!
of course the problem is in this lines of code
let login = self.storyboard?.instantiateViewController(withIdentifier: "login") as! LoginVC
self.present(login, animated: true, completion: nil)
as far as I know, if the view is stacked in the layer of navigation controller, then if I want to move to another view controller I have to use perform segue method.
But for this case, between homeVC and LoginVC are not stacked in the same navigation controller. so no hierarchy. thats why I use that line of code to move to another view controller (loginVC). but I don't understand why it is said "view is not in the window hierarchy!"
So what should I do to omit that warning?
Move code to viewDidAppear
override func viewDidAppear(_ animated:Bool) {
super.viewDidAppear(true)
// to check whether the user has already logged in or not
Auth.auth().addStateDidChangeListener { (auth, user) in
if user == nil {
let login = self.storyboard?.instantiateViewController(withIdentifier: "login") as! LoginVC
self.present(login, animated: true, completion: nil)
}
}
print("user enter homeVC")
}
Your LoginVC is perfectly fine.
However, you need to change your HomeVC as #Sh_Khan suggested and move the testing code from viewDidLoad to viewDidAppear:
import UIKit
import Firebase
class HomeVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
// HomeVC.view was added to a view hierarchy
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
// to check whether the user has already logged in or not
Auth.auth().addStateDidChangeListener { (auth, user) in
if user == nil {
let login = self.storyboard?.instantiateViewController(withIdentifier: "login") as! LoginVC
self.present(login, animated: true, completion: nil)
}
}
}
}
Explanation
Your viewDidLoad method gets called before the viewController gets presented, so it at that moment it cannot really present another view controller (since it itself is not presented), viewDidLoad documentation:
Called after the controller's view is loaded into memory.
This method is called after the view controller has loaded its view hierarchy into memory. This method is called regardless of whether the view hierarchy was loaded from a nib file or created programmatically in the loadView() method. You usually override this method to perform additional initialization on views that were loaded from nib files.
In that moment the viewController is not in the window hierarchy yet.
viewDidAppear however gets called when the view is presented and becomes a part of the window hierarchy, viewDidAppear documentation:
Notifies the view controller that its view was added to a view hierarchy.
You can override this method to perform additional tasks associated with presenting the view. If you override this method, you must call super at some point in your implementation.
Don't forget to call super.viewDidAppear during overriding it.
TLDR; You should move your code to viewDidAppear
viewDidLoad()
This method is called after the view controller has loaded its view hierarchy into memory. This method is called regardless of whether the view hierarchy was loaded from a nib file or created programmatically in the loadView() method. You usually override this method to perform additional initialization on views that were loaded from nib files.
Apple docs
So the view is only in memory yet and not in the hierarchy. You should move it to viewDidAppear
viewDidAppear()
Notifies the view controller that its view was added to a view hierarchy. Apple docs
As Sh_Khan said, move the lines:
let login = self.storyboard?.instantiateViewController(withIdentifier: "login") as! LoginVC
self.present(login, animated: true, completion: nil)
in viewDidAppear() method; when viewDidLoad() gets called, the view controller it's not added on the view hierarchy yet, it's not visible and it cannot present another view controller.
The reason for such kind of error is: You are trying present (open) two view controllers simultaneously (view of first presenting view controller is just started and you may be trying to present second view controller).
You should move your code (for view controller presentation/navigation) to viewDidAppear. Your main view of existing view controller (from where you are presenting new view controller) is not ready/loaded.
You should move it to viewDidAppear.
Here is sample code:
Swift 4
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
// instantiate your view controller either using storyboard or class or any other way....
if let newVC = self.storyboard?.instantiateViewController(withIdentifier: "NewViewController") as? NewViewController {
self.present(newVC, animated: true, completion: nil)
}
}
In your case/code, solution is:
override func viewDidLoad() {
super.viewDidLoad()
// Move your code from here (viewDidLoad) to viewDidAppear
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
// to check whether the user has already logged in or not
Auth.auth().addStateDidChangeListener { (auth, user) in
if user == nil {
let login = self.storyboard?.instantiateViewController(withIdentifier: "login") as! LoginVC
self.present(login, animated: true, completion: nil)
}
}
print("user enter homeVC")
}
Look at the difference between both view controller life cycle.
viewDidLoad
This method is called after the view controller has loaded its view hierarchy into memory. This method is called regardless of whether the view hierarchy was loaded from a nib file or created programmatically in the loadView() method. You usually override this method to perform additional initialization on views that were loaded from nib files.
See more about: viewDidLoad
viewDidAppear
Notifies the view controller that its view was added to a view hierarchy.
See more about: viewDidAppear
At this point in your code, the view controller's view has only been created but not added to any view hierarchy. If you want to present from that view controller as soon as possible you should do it in viewDidAppear to be safest.
I'll give an example of what I want so it's not so confusing:
Example:
Let's say that I have a map that adds every time that my user scrolls 3 annotations dynamically. Now I have a button under the map and when I press it I go to another viewController do what I want and get back to the viewController with the map, now I want to find all the annotations that my map had and not reload the view at all.
I used to use this function that I made to move between viewControllers:
func move(identifier: String , viewController : UIViewController) -> Void {
let mstoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc: UIViewController = mstoryboard.instantiateViewControllerWithIdentifier(identifier)
viewController.presentViewController(vc, animated: true, completion: nil)
}
I also tried this:
let vc = self.storyboard?.instantiateViewControllerWithIdentifier("view") as? MyViewcontroller
self.presentViewController(vc!, animated: true, completion: nil)
These two when I use them the viewcontroller that appears is calling viewDidload so its like it appeared for the first time.
Another example is the tabBarViewController if you notice when you navigate through tabs nothing reloads (only function that is called is viewDidAppear )
EDIT
test file
The problem is caused by the fact that the map controller gets deallocated when navigating back to the other controller, and another one is created when you want to move again to the map screen.
What you need is to hold on onto the same controller instance, and present that one. Keeping a strong reference in the presenting controller would suffice.
class PresentingController {
// making the property lazy will result in the getter code
// being executed only when asked the first time
lazy var mapController = { () -> UIViewController in
let mstoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
return mstoryboard.instantiateViewControllerWithIdentifier("mapControllerIdentifier")
}()
func moveToMap() {
// simply use the mapController property
// the property reference will make sure the controller won't
// get deallocated, so every time you navigate to that screen
// you'll get the same controller
presentViewController(mapController, animated: true, completion: nil)
}
}
According to the same project you posted, you instantiate a new UIViewController when going from view 2 back to view 1 and that is why your viewDidLoad gets called again and your entire map view is reloaded.
In your sample project, instead of
lazy var mapController2 = { () -> UIViewController in
let mstoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
return mstoryboard.instantiateViewController(withIdentifier: "first")
}
You should just dismiss your view 2 on the button press.
#IBAction func butto(_ sender: AnyObject) {
//Your initial code
//PresentingController().moveToMap(self, flag: 1)
self.dismiss(animated: true, completion: nil)
}
When you present a new UIViewController, the older UIViewController is not removed from memory, it is just hidden behind the new UIViewController. So whenever you wish to go back to a UIViewController with the previous state maintained, all you need to do is close the new UIViewController
However, if you are doing some tasks that you performed on your second UIViewController that you wish to be reflected in your initial UIViewController, you will have to setup closures to update your initial UIViewController.
I have a ViewController: if a user is not logged in, I open modally a new controller, so that the user can login. The opening is done this way:
if(!loggedIn){
self.performSegue(withIdentifier:"loginView", sender:self)
}
After login, I want to dismiss this modal and come back to my viewcontroller: this is very easy to do, but I want another thing. I want the presenting view controller call this method before I dismiss my modal:
func goToContent(animated:Bool){
let viewController:ContentViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Content") as! ContentViewController
self.navigationController!.pushViewController(viewController, animated: animated)
}
Is this possible? From my modal I could not get a reference to the presenting viewController. That is: I tried the following, but I don't know if this is the right way to proceed:
let vc:ViewController = ViewController()
vc.goToContent(animated:false)
This works but aren't there better solutions?
[Edit to reply to a question in the comments]
I implemented a delegate this way:
in the ViewController:
class ViewController: UIViewController, LoginViewControllerDelegate {
var loginViewController:LoginViewController = LoginViewController()
override func viewDidLoad() {
super.viewDidLoad()
loginViewController.delegate = self
}
In LoginViewController file, just before the class declaration:
protocol LoginViewControllerDelegate: class {
func goToContent(animated:Bool)
}
Inside LoginViewController:
weak var delegate: LoginViewControllerDelegate?
in its view did load (just for testing: I simply put a print inside the body of goToContent):
delegate?.goToContent()
You need to create a delegate of ContentViewController and in that delegate you need to add this method goToContent.
Now when you are logged in successfully, you need to call this delegate method. It will work.
I meet a strange problem: I made 2 view controllers for wich I can switch the view with code:
var currentViewController:UIViewController=UIApplication.shared.keyWindow!.rootViewController!
func showController()
{
let ViewControllernew1 = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "viewController2")
currentViewController.present(ViewControllernew1, animated: true, completion: nil)
}
My app open correctly to the first view controller, then, when I click on the button created on a sprite kit scene, I can switch the view to my new view controller successfully (I get my second scene successfully showed) but then, I can not change anymore my view controller after this switch. If I click again on the button, I get this message:
Attempt to present on Test_Vuforia.GameViewController: 0x12f549610 whose view is not in the window hierarchy!
Do you know what is the problem ? I understand I'm in the root position so that I can not change anymore my view controller after having switched it, but how to change that ?
Thanks !
Edit:
My code is used inside a SKScene and not from a UIVewController and I get this error when I use the suffix self. : Value of type View (SKScene) has no member 'present'.
I'm creating an augmented reality game with Vuforia and I need to switch AR view with SKScene.
Issue
Current viewController is not the rootViewController from UIApplication. So you should find the current viewController which is visible and then present it from there.
Solution
Simply find the topViewController on your UIApplication Stack, and from there present your controller.
let newViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "viewController2")
UIApplication.topViewController()?.present(newViewController, animated: true, completion: nil)
This extension of UIApplication comes in handy for your case
extension UIApplication {
class func topViewController(base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
if let nav = base as? UINavigationController {
return topViewController(base: nav.visibleViewController)
}
if let tab = base as? UITabBarController {
if let selected = tab.selectedViewController {
return topViewController(base: selected)
}
}
if let presented = base?.presentedViewController {
return topViewController(base: presented)
}
return base
}
}
References: Gist
Calling function in viewDidAppear helps in my case. Solution for Swift 3:
In your Main Controller:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
showTutorialModally()
}
func showTutorialModally() {
let tutorialViewController = TutorialViewController()
tutorialViewController.modalPresentationStyle = .overCurrentContext
present(tutorialViewController, animated: true, completion: nil)
}
In your Tutorial Controller:
view.backgroundColor = UIColor.clear
view.isOpaque = false
Use the extension below to retrieve the next available controller in the stack.
Swift 3
extension UIResponder {
func next<T: UIResponder>(_ type: T.Type) -> T? {
return next as? T ?? next?.next(type)
}
}
Swift 2.3
extension UIResponder {
func nextResponder<T: UIResponder>(_ type: T.Type) -> T? {
return nextResponder() as? T ?? nextResponder()?.nextResponder(type)
}
}
Inside your SKScene, view?.next(UIViewController.self) gives you the next available UIViewController in the hierarchy.
Add this extension to a group in your project called Categories, if this group does not exist already create it, then create a new file called UIResponder+NextOfType.swift and paste the extension.
Xcode error significance for roughly: this view is not in the Window of the view hierarchy.
What I don't think the above answer questions, but maybe you might have wondered why this would happen.
But I find that you are the reasons for this problem is likely to be in the ViewController life cycle at ViewDidLoading switch view Code execution inside.
Reason is probably that, when the ViewController implementation allco init during initialization, it will be executed asynchronously viewWillLoad - > viewDidLoad... -- -- -- -- > viewDidApper. Then may be in code execution to the viewDidLoad. The ViewController may not assign values to the Window. The rootViewController. So we directly use [self presentViewController:] will appear this error.
It is recommended that you move the code of the switch to ViewDidApper.
I hope it will help you.
Probably your rootViewController is not the current ViewController. Either you presented or pushed a new UIViewController on top of it.
The viewController's view is not in the
window's view hierarchy at the point that it has been loaded (when
the viewDidLoad message is sent), but it is in the window
hierarchy after it has been presented (when the viewDidAppear:
message is sent). if you calling showController method from
viewDidLoad just call it from viewDidAppear method
Do something like:
let vc: UIViewController = (self.storyboard?.instantiateViewControllerWithIdentifier("viewController2"))!
self.presentViewController(vc, animated: true, completion: nil)
// OR
self.navigationController?.pushViewController(vc, animated: true)
Use like this
let vc = self.view?.window?.rootViewController
func showController()
{
let ViewControllernew1 = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "viewController2")
vc.present(ViewControllernew1, animated: true, completion: nil)
}
Maybe the issue is with the currentViewController.
I am dismissing a popover view controller programmatically. How can i detect that in my first view controller? Is there a way to send values from the popover to the first one?
Note: popoverPresentationControllerDidDismissPopover does not work when dismissed programmatically.
Any proposition?
this is my code in the main view controller:
let addFriendsPopoverViewController = storyboard?.instantiateViewControllerWithIdentifier("HomeEmotionPopOver") as! EmotionPopOverViewController
addFriendsPopoverViewController.modalInPopover = true
addFriendsPopoverViewController.modalPresentationStyle = UIModalPresentationStyle.Popover
addFriendsPopoverViewController.preferredContentSize = CGSizeMake(100, 100)
let popoverMenuViewController = addFriendsPopoverViewController.popoverPresentationController
popoverMenuViewController!.permittedArrowDirections = .Any
popoverMenuViewController!.delegate = self
popoverMenuViewController!.sourceView = self.view
let height = (self.tableView.rowHeight - HeartAttributes.heartSize / 2.0 - 10) + (self.tableView.rowHeight * CGFloat((sender.view?.tag)!)) - 50
popoverMenuViewController!.sourceRect = CGRect(
x: 30,
y: height,
width: 1,
height: 1)
presentViewController(
addFriendsPopoverViewController,
animated: true,
completion: nil)
and in the popover view controller, i'm dismissing it from a button IBAction:
#IBAction func dismissPop(sender: AnyObject) {
self.dismissViewControllerAnimated(true, completion: nil)
}
The way you have worded your question is that you are looking for a function on the main view controller that is called when a popover is dismissed.
This technically happens with viewDidAppear(animated:). However, it isn't a full proof solution. If your popover doesn't cover the full screen context, this function wont fire, so it is an unreliable solution.
Really what you want is to invoke a function from the popover alerting the main view controller that it has finished/dismissed. This is easily done with a delegate protocol
protocol PopoverDelegate {
func popoverDismissed()
}
class PopoverViewController {
weak var delegate: PopoverDelegate?
//Your Popover View Controller Code
}
Add the protocol conformance to your main view controller
class MainViewController: UIViewController, PopoverDelegate {
//Main View Controller code
}
Then you need to set the delegate to for the popover to be the main view controller.
let addFriendsPopoverViewController = storyboard?.instantiateViewControllerWithIdentifier("HomeEmotionPopOver") as! EmotionPopOverViewController
addFriendsPopoverViewController.delegate = self
//The rest of your code
Finally, call this delegate function from your popover view controller when you dismiss.
#IBAction func dismissPop(sender: AnyObject) {
dismissViewControllerAnimated(true, completion: nil)
delegate?.popoverDismissed()
}
And in your main view controller, implement the delegate method
func popoverDismissed() {
//Any code to run when popover is dismissed
}
The trick is to dismiss the segue yourself but make it seem that the user initiated it so it can be detected by the delegate method popoverPresentationControllerDidDismissPopover().
I did it by adding a completion closure to the presentingViewController dismiss() function and directly invoked the routine.
if let pvc = self.presentingViewController {
var didDismiss : ((UIPopoverPresentationController) -> Void)? = nil
if let delegate = popoverPresentationController?.delegate {
// check it is okay to dismiss the popover
let okayToDismiss = delegate.popoverPresentationControllerShouldDismissPopover?(popoverPresentationController!) ?? true
if okayToDismiss {
// create completion closure
didDismiss = delegate.popoverPresentationControllerDidDismissPopover
}
}
// use local var to avoid memory leaks
let ppc = popoverPresentationController
// dismiss popover with completion closure
pvc.dismiss(animated: true) {
didDismiss?(ppc!)
}
}
It is working fine for me.