Attempt to present UIViewController on UIViewController whose view is not in the window hierarchy

Question

Just started using Xcode 4 5 and I got this error in the console      Warning  Attempt to present  lt  finishViewController  0x1e56e0a0   on  lt  ViewController  0x1ec3e000  whose view is not in the window hierarchy    The view is still being presented and everything in the app is working fine  Is this something new in iOS 6   This is the code I m using to change between views   UIStoryboard  storyboard   self storyboard  finishViewController  finished     storyboard instantiateViewControllerWithIdentifier   finishViewController      self presentViewController finished animated NO completion NULL

User · Answer

I just had this issue too  but it had nothing to do with the timing  I was using a singleton to handle scenes  and I set it as the presenter  In other words  Self  wasn t hooked up to anything  I just made its inner  scene  the new presenter and voila  it worked   Voila loses its touch after you learn its meaning  heh    So yeah  it s not about  magically finding the right way   it s about understanding where your code stands and what it s doing  I m happy Apple gave such a plain-English warning message  even with emotion to it  Kudos to the apple dev who did that

User · Answer

If other solutions does not look good for some reason  you can still use this good old workaround of presenting with the delay of 0  like this   dispatch after 0  dispatch get main queue           finishViewController  finished    self storyboard instantiateViewControllerWithIdentifier   finishViewController         self presentViewController finished animated NO completion NULL             While I ve seen no documented guarantee that your VC would be on the view hierarchy on the time dispatch block is scheduled to execution  I ve observed it would work just fine    Using delay of e g  0 2 sec is also an option  And the best thing - this way you don t need to mess with boolean variable in viewDidAppear

User · Answer

With Swift 3     Another possible cause to this  which happened to me  was having a segue from a tableViewCell to another ViewController on the Storyboard  I also used override func prepare for segue  UIStoryboardSegue  sender  Any      when the cell was clicked   I fixed this issue by making a segue from ViewController to ViewController

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If you have AVPlayer object with played video you have to pause video first

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viewWillLayoutSubviews and viewDidLayoutSubviews  iOS 5 0   can be used for this purpose  They are called earlier than viewDidAppear

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Swift 5 I call present in viewDidLayoutSubviews as presenting in viewDidAppear causes a split second showing of the view controller before the modal is loaded which looks like an ugly glitch make sure to check for the window existence and execute code just once var alreadyPresentedVCOnDisplay   false  override func viewDidLayoutSubviews                  super viewDidLayoutSubviews               we call present in viewDidLayoutSubviews as        presenting in viewDidAppear causes a split second showing         of the view controller before the modal is loaded          guard let     view  window else              window must be assigned         return                if  alreadyPresentedVCOnDisplay           alreadyPresentedVCOnDisplay   true         present

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I fixed it by moving the start   function inside the dismiss completion block   self tabBarController dismiss animated  false      self start       Start contains two calls to self present   one for a UINavigationController and another one for a UIImagePickerController   That fixed it for me

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TL DR You can only have 1 rootViewController and its the most recently presented one  So don t try having a viewcontroller present another viewcontroller when it s already presented one that hasn t been dismissed   After doing some of my own testing I ve come to a conclusion   If you have a rootViewController that you want to present everything then you can run into this problem   Here is my rootController code  open is my shortcut for presenting a viewcontroller from the root    func open controller UIViewController        if  Context ROOTWINDOW rootViewController    nil                Context ROOTWINDOW rootViewController   ROOT VIEW CONTROLLER         Context ROOTWINDOW makeKeyAndVisible              ROOT VIEW CONTROLLER presentViewController controller  animated  true  completion          If I call open twice in a row  regardless of time elapsed   this will work just fine on the first open  but NOT on the second open  The second open attempt will result in the error above    However if I close the most recently presented view then call open  it works just fine when I call open again  on another viewcontroller    func close controller UIViewController        ROOT VIEW CONTROLLER dismissViewControllerAnimated true  completion  nil      What I have concluded is that the rootViewController of only the MOST-RECENT-CALL is on the view Hierarchy  even if you didn t dismiss it or remove a view   I tried playing with all the loader calls  viewDidLoad  viewDidAppear  and doing delayed dispatch calls  and I have found that the only way I could get it to work is ONLY calling present from the top most view controller

User · Answer

Swift 5 - Background Thread If an alert controller is executed on a background thread then the  quot Attempt to present     whose view is not in the window hierarchy quot  error may occur  So this  present alert  animated  true  completion  nil        Was fixed with this  DispatchQueue main async    weak self  in     self  present alert  animated  true  completion  nil

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You can also get this warning when performing a segue from a view controller that is embedded in a container  The correct solution is to use segue from the parent of container  not from container s view controller

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For Display any  subview to main view Please use following code  UIViewController  yourCurrentViewController    UIApplication sharedApplication  keyWindow rootViewController   while  yourCurrentViewController presentedViewController        yourCurrentViewController   yourCurrentViewController presentedViewController      yourCurrentViewController presentViewController composeViewController animated YES completion nil     For Dismiss any  subview from main view Please use following code  UIViewController  yourCurrentViewController    UIApplication sharedApplication  keyWindow rootViewController   while  yourCurrentViewController presentedViewController        yourCurrentViewController   yourCurrentViewController presentedViewController      yourCurrentViewController dismissViewControllerAnimated YES completion nil

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I ve ended up with such a code that finally works to me  Swift   considering you want to display some viewController from virtually anywhere  This code will obviously crash when there is no rootViewController available  that s the open ending  It also does not include usually required switch to UI thread using   dispatch sync dispatch get main queue          guard  NSBundle mainBundle   bundlePath hasSuffix   appex   else          return     skip operation when embedded to App Extension            if let delegate   UIApplication sharedApplication   delegate           delegate window   rootViewController  presentViewController viewController  animated  true  completion       - gt  Void in                optional completion code

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I had this issue  and the root cause was subscribing to a button click handler  TouchUpInside  multiple times   It was subscribing in ViewWillAppear  which was being called multiple times since we had added navigation to go to another controller  and then unwind back to it

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Another potential cause   I had this issue when I was accidentally presenting the same view controller twice   Once with performSegueWithIdentifer sender  which was called when the button was pressed  and a second time with a segue connected directly to the button    Effectively  two segues were firing at the same time  and I got the error  Attempt to present X on Y whose view is not in the window hierarchy

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I fixed this error with storing top most viewcontroller into constant which is found within while cycle over rootViewController   if var topController   UIApplication shared keyWindow  rootViewController       while let presentedViewController   topController presentedViewController           topController   presentedViewController           topController present controller  animated  false  completion  nil         topController should now be your topmost view controller

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Probably  like me  you have a wrong root viewController  I want to display a ViewController in a non-UIViewController context   So I can t use such code    self presentViewController     So  I get a UIViewController       UIApplication sharedApplication  delegate  window  rootViewController    For some reason  logical bug   the rootViewController is something other than expected  a normal UIViewController   Then I correct the bug  replacing rootViewController with a UINavigationController  and the problem is gone

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This works for to present any view controller  if you have navigation controller available  self navigationController  present MyViewController  animated  true  completion  nil  Also   I can able to present alerts and mail controller also

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This kind of warning can mean that You re trying to present new View Controller through Navigation Controller while this Navigation Controller is currently presenting another View Controller  To fix it You have to dismiss currently presented View Controller at first and on completion present the new one  Another cause of the warning can be trying to present View Controller on thread another than main

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I had similar issue on Swift 4 2 but my view was not presented from the view cycle  I found that  I had multiple segue to be presented at same time  So I used dispatchAsyncAfter    func updateView       DispatchQueue main asyncAfter deadline   now     0 1     weak self  in     for programmatically presenting view controller     present viewController  animated  true  completion  nil     For Story board segue  you will also have to setup prepare segue for this to work    self  performSegue withIdentifier   Identifier   sender  nil

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With your main window  there will likely always be times with transitions that are incompatible with presenting an alert  In order to allow presenting alerts at any time in your application lifecycle  you should have a separate window to do the job       independant window for alerts  interface AlertWindow  UIWindow     void presentAlertWithTitle  NSString   title message  NSString   message    end   implementation AlertWindow     AlertWindow   sharedInstance       static AlertWindow  sharedInstance      static dispatch once t onceToken      dispatch once  amp onceToken             sharedInstance     AlertWindow alloc  initWithFrame UIScreen mainScreen bounds               return sharedInstance        void presentAlertWithTitle  NSString   title message  NSString   message          Using a separate window to solve  Warning  Attempt to present  lt UIAlertController gt  on  lt UIViewController gt  whose view is not in the window hierarchy       UIWindow  shared   AlertWindow sharedInstance      shared userInteractionEnabled   YES      UIViewController  root   shared rootViewController      UIAlertController  alert    UIAlertController alertControllerWithTitle title message message preferredStyle UIAlertControllerStyleAlert       alert modalInPopover   true       alert addAction  UIAlertAction actionWithTitle   OK  style UIAlertActionStyleCancel handler   UIAlertAction  action            shared userInteractionEnabled   NO           root dismissViewControllerAnimated YES completion nil                 root presentViewController alert animated YES completion nil      -  instancetype initWithFrame  CGRect frame       self    super initWithFrame frame        self userInteractionEnabled   NO      self windowLevel   CGFLOAT MAX      self backgroundColor   UIColor clearColor      self hidden   NO      self rootViewController   UIViewController new        NSNotificationCenter defaultCenter addObserver self                                            selector  selector bringWindowToTop                                                  name UIWindowDidBecomeVisibleNotification                                              object nil        return self         Bring AlertWindow to top when another window is being shown  -  void bringWindowToTop  NSNotification   notification       if    notification object isKindOfClass  AlertWindow class              self hidden   YES          self hidden   NO            end   Basic usage that  by design  will always succeed    AlertWindow presentAlertWithTitle   My title  message   My message

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I also encountered this problem when I tried to present a UIViewController in viewDidLoad  James Bedford s answer worked  but my app showed the background first for 1 or 2 seconds   After some research  I ve found a way to solve this using the addChildViewController   -  void viewDidLoad                self view addSubview  navigationViewController view        self addChildViewController  navigationViewController

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Where are you calling this method from  I had an issue where I was attempting to present a modal view controller within the viewDidLoad method  The solution for me was to move this call to the viewDidAppear  method   My presumption is that the view controller 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      Caution  If you do make a call to presentViewController animated completion  in the viewDidAppear  you may run into an issue whereby the modal view controller is always being presented whenever the view controller s view appears  which makes sense   and so the modal view controller being presented will never go away     Maybe this isn t the best place to present the modal view controller  or perhaps some additional state needs to be kept which allows the presenting view controller to decide whether or not it should present the modal view controller immediately

User · Answer

It s working fine try this Link  UIViewController  top    UIApplication sharedApplication  keyWindow rootViewController   top presentViewController secondView animated YES completion  nil

User · Answer

The message appear as warning and sometimes the code refuses to work    Needs Citation  Newer SDK s might have strict rules    I have encountered it for more than one reason  mostly complicated viewcontroller scenarios  Here s an example   Scenario  MainViewController  responsible to load  ViewControllerA  amp  ViewControllerB    Present ViewControllerA from MainViewController and without dismissing the ViewControllerA you try to present viewControllerB from MainViewController  using a delegate method    In this scenario  you d have to make sure your ViewControllerA is dismissed and then the ViewControllerB is called   Because after presenting ViewControllerA  ViewControllerA becomes responsible for displaying views and viewcontrollers and when MainViewController attempts to load another viewcontoller  it refuses to work with throwing a warning

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Sadly  the accepted solution did not work for my case  I was trying to navigate to a new View Controller right after unwind from another View Controller   I found a solution by using a flag to indicate which unwind segue was called    IBAction func unwindFromAuthenticationWithSegue segue  UIStoryboardSegue        self shouldSegueToMainTabBar   true     IBAction func unwindFromForgetPasswordWithSegue segue  UIStoryboardSegue        self shouldSegueToLogin   true     Then present the wanted VC with present   viewControllerToPresent  UIViewController   override func viewWillAppear   animated  Bool        super viewWillAppear animated      let storyboard   UIStoryboard name   Main   bundle  nil      if self shouldSegueToMainTabBar           let mainTabBarController   storyboard instantiateViewController withIdentifier   mainTabBarVC   as  MainTabBarController         self present mainTabBarController  animated  true          self shouldSegueToMainTabBar   false           if self shouldSegueToLogin           let loginController   storyboard instantiateViewController withIdentifier   loginVC   as  LogInViewController         self present loginController  animated  true          self shouldSegueToLogin   false           Basically  the above code will let me catch the unwind from login SignUp VC and navigate to the dashboard  or catch the unwind action from forget password VC and navigate to the login page

User · Answer

I had the same problem  I had to embed a navigation controller and present the controller through it  Below is the sample code   -  void viewDidLoad        super viewDidLoad          Do any additional setup after loading the view  typically from a nib       UIImagePickerController  cameraView     UIImagePickerController alloc init        cameraView setSourceType UIImagePickerControllerSourceTypeCamera        cameraView setShowsCameraControls NO        UIView  cameraOverlay     UIView alloc initWithFrame CGRectMake 0  0  768  1024        UIImageView  imageView     UIImageView alloc initWithImage  UIImage imageNamed   someImage          imageView setFrame CGRectMake 0  0  768  1024         cameraOverlay addSubview imageView         cameraView setCameraOverlayView imageView         self navigationController presentViewController cameraView animated NO completion nil          self presentViewController cameraView animated NO completion nil     this will cause view is not in the window hierarchy error

User · Answer

It happened to me that the segue in the storyboard was some kind of broken  Deleting the segue  and creating the exact same segue again  solved the issue

User · Answer

In my situation  I was not able to put mine in a class override  So  here is what I got   let viewController   self    I had viewController passed in as a function                               but otherwise you can do this      Present the view controller let currentViewController   UIApplication shared keyWindow  rootViewController currentViewController  dismiss animated  true  completion  nil   if viewController presentedViewController    nil       currentViewController  present alert  animated  true  completion  nil    else       viewController present alert  animated  true  completion  nil

User · Answer

I had the same issue  The problem was  the performSegueWithIdentifier was triggered by a notification  as soon as I put the notification on the main thread the warning message was gone

User · Answer

Have to write below line   self searchController definesPresentationContext   true   instead of   self definesPresentationContext   true   in UIViewController

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I found this bug arrived after updating Xcode  I believe to Swift 5  The problem was happening when I programatically launched a segue directly after unwinding a view controller   The solution arrived while fixing a related bug  which is that the user was now able to unwind segues by swiping down the page  This broke the logic of my program    It was fixed by changing the Presentation mode on all the view controllers from Automatic to Full Screen   You can do it in the attributes panel in interface builder  Or see this answer for how to do it programatically

User · Answer

My issue was I was performing the segue in UIApplicationDelegate s didFinishLaunchingWithOptions method before I called makeKeyAndVisible   on the window

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In case it helps anyone  my issue was extremely silly  Totally my fault of course  A notification was triggering a method that was calling the modal  But I wasn t removing the notification correctly  so at some point  I would have more than one notification  so the modal would get called multiple times  Of course  after you call the modal once  the viewcontroller that calls it it s not longer in the view hierarchy  that s why we see this issue  My situation caused a bunch of other issue too  as you would expect   So to summarize  whatever you re doing make sure the modal is not being called more than once

User · Answer

You can call your segues or present  push codes inside this block  override func viewDidLoad         super viewDidLoad       OperationQueue main addOperation              push or present the page inside this block

[ios] Attempt to present UIViewController on UIViewController whose view is not in the window hierarchy

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