VisionOS app with UIKit : error with window visibility

Question

I am running into an exception whenever I try to open the app's window in visionOS simulator. The exception error message says:

"Thread 1: "Error in UIKit client: window visibility must match its layer visibility!""

This is the same code that runs just fine on iOS where I setup the app's window and tab bar controller in code:

- (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    // Setup the UI - Override point for customization after app launch
    UIWindowScene *firstScene = (UIWindowScene *) [[[[UIApplication sharedApplication] connectedScenes] allObjects] firstObject];
    self.mainWindow = [[UIWindow alloc] initWithWindowScene:firstScene];
    self.mainWindow.backgroundColor = [UIColor systemBackgroundColor];
    
    self.tabController = [[UITabBarController alloc] init];
    [self.tabController definesPresentationContext];
    
    self.mainWindow.rootViewController = self.tabController;
    [self.mainWindow makeKeyAndVisible];
    // setup the tab bar later

The exception comes from the makeKeyAndVisible line. I'm not sure what I need to do differently for a visionOS app to make it work.

I'm using Xcode 15.1 Beta 2.

796

Posted by

zulfishah

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Answer 1

Are you sure you're getting a UIWindowScene here (that is, firstScene is non-nil)?

This isn't how we would expect you to connect your first window when using scenes – we would instead expect you to create your first window in your scene delegate's -scene:willConnectToSession:options: method instead.

I would suspect that your app is simply getting launched (and getting -application:willFinishLaunchingWithOptions:) before your first scene has been connected.

Posted by

Rincewind

The firstScene object isn't nil, thought the windows and keyWindow properties are both nil. The assertion I get is: *** Assertion failure in BOOL _UIWindowSceneCompatibleIsHidden(UIWindow *__strong)(), UIWindowScene.m:2732 Is there a way I can inspect it?

—
zulfishah
I created FB13325773 with a sample project, if you're able to take a look. I was able to reproduce the issue in a new Xcode project, where I remove the storyboard and try to create the app's window programatically, this time with UIWindowSceneDelegate. Same problem ... app works fine on iOS simulator, but crashes on the 'makeKeyAndVisible' call when running on Apple Vision simulator.

—
zulfishah

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Answer 2

Thanks. The firstScene object isn't nil, until it's windows or keyWindow properties are both nil. Could that be the problem?

This is what the object looks like in the debugger:

<UIWindowScene: 0x106b0ef40; role: UIWindowSceneSessionRoleApplication; activationState: UISceneActivationStateForegroundActive> {
    session = <UISceneSession: 0x600001793200; persistentIdentifier: com.myapp.name> {
        configuration = <UISceneConfiguration: 0x600001794c40; name: 0x0>;
    };
    delegate = (nil);
    screen = <UIScreen: 0x10711b1a0; bounds: {{0, 0}, {1366, 1024}}; mode: <UIScreenMode: 0x600000268bc0; size = 2732.000000 x 2048.000000>>;
}

I never adopted the UIScenes and UIWindowsScene APIs from iOS13+, and I run my iOS app as a single-window app. Would I have to change that to be able to run my app as a native VisionOS app?

Posted by

zulfishah

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Answer 3

This is still not resolved with Xcode 15.1 Beta3. I created a I created FB13325773 with a sample project, so it's a problem for 'new' projects as well.

Posted by

zulfishah

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Answer 4

The issue still persists with Xcode 15.2 Beta 1. Just to reiterate: I created FB13325773 with a sample project

Posted by

zulfishah

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Answer 5

After much time wastage, it turns out that the problem is caused by setting the window's backgroundColor (for some reason). So it works fine after commenting out this line:

self.mainWindow.backgroundColor = [UIColor systemBackgroundColor];

Posted by

zulfishah

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VisionOS app with UIKit : error with window visibility

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