migration to UIScene required

[kambala-decapitator]

There's console warning on app launch in Xcode 16.2:

CLIENT OF UIKIT REQUIRES UPDATE: This process does not adopt UIScene lifecycle. This will become an assert in a future version.

[wutschel]

I am not seeing this with Xcode 16.2 and iPhone/iPad 18.2 simulators. What device/sim do you use?

[kambala-decapitator]

iPhone running 18.4.1

[wutschel]

Migration is basically prepared and can be done once we change the minimum iOS version to 13.

Code:
https://github.com/wutschel/Official-Kodi-Remote-iOS/tree/migrate_UIScene

Is it required to also change the life cycle methods, like applicationWillResignActive / sceneWillResignActive to UIWindowScene?

Issue I still have is that on iPad there is a layout issue where the status line and the bottom safe area are not kept free. Still need to dig into this.

Screenshot:
https://ibb.co/WpNbpSFd

[kambala-decapitator]

change the minimum iOS version to 13

It's not required. The scene methods will simply be called on 13+ and the appdelegate ones - on 12.

All methods that have a counterpart in scene must be implemented. (If they're implemented in the appdelegate of course)

[wutschel]

Issue I still have is that on iPad there is a layout issue where the status line and the bottom safe area are not kept free. Still need to dig into this.

Looks like the reason is that keyWindow in UIApplication.keyWindow is nil. This only happens for the iPad and not the iPhone. You have good hint for me where I should dig further?

[kambala-decapitator]

Issue I still have is that on iPad there is a layout issue where the status line and the bottom safe area are not kept free. Still need to dig into this.

Looks like the reason is that keyWindow in UIApplication.keyWindow is nil. This only happens for the iPad and not the iPhone. You have good hint for me where I should dig further?

yes, because now you should use UIScene API for that

[wutschel]

I had following prepared via another PR a while back.

+ (UIWindowScene*)scene {
    NSArray *scenes= UIApplication.sharedApplication.connectedScenes.allObjects;
    UIWindowScene *scene = scenes[0];
    return scene;
}

+ (UIWindow*)keyWindow {
    UIWindow *windowRoot = nil;
    UIWindowScene *scene = [AppDelegate scene];
    NSArray *windows = scene.windows;
    for (UIWindow *window in windows) {
        if (window.isKeyWindow) {
            windowRoot = window;
            break;
        }
    }
    return windowRoot;
}

+ (UIStatusBarManager*)statusBarManager {
    UIWindowScene *scene = [AppDelegate scene];
    return scene.statusBarManager;
}

+ (UIInterfaceOrientation)interfaceOrientation {
    UIWindowScene *scene = [AppDelegate scene];
    return scene.interfaceOrientation;
}

But still window.isKeyWindow is NO. The only window in that loop is the iPad's main view controller.

[wutschel]

Instead of

for (UIWindow *window in windows) {
    if (window.isKeyWindow) {
        windowRoot = window;
        break;
    }
}
return windowRoot;

I could also simply use return windows[0], as the app does not support multiple windows, right? But somehow this feels not a good solution.

Edit: At least I found the reason for isKeyWindow being false. This loop is running even before makeKeyAndVisible is called. Need to dig deeper into it.

Edikt 2: Looks like the main reason is that some layout related stuff is done in several view controller's viewDidLoad before the window is ready. Just ensuring makeKeyAndVisible is called before viewDidLoad is not enough. In consequence, some of the top and bottom paddings are just 0. The layout related stuff done inside viewWillLayoutSubviews seems to work as expected.

[kambala-decapitator]

I could also simply use return windows[0], as the app does not support multiple windows, right? But somehow this feels not a good solution.

it's fine as long as we have just a single window. But isn't this what you're looking for? https://developer.apple.com/documentation/uikit/uiwindowscene/keywindow?language=objc

Looks like the main reason is that some layout related stuff is done in several view controller's viewDidLoad before the window is ready

normally viewDidLoad shouldn't have anything related to layout, viewWillLayoutSubviews / viewDidLayoutSubviews is the proper place when you need final dimensions

[wutschel]

it's fine as long as we have just a single window. But isn't this what you're looking for? https://developer.apple.com/documentation/uikit/uiwindowscene/keywindow?language=objc

Yup, I now compressed this to

+ (UIWindow*)keyWindow {
    /* WORKAROUND: Instead of keyWindow we return the first window. As this app only supports
     * a single window, this works and avoids a problem caused by the implementation of most app's
     * UIViewControllers which use keyWindow.safeAreaInset in viewDidLoad instead of willLayoutSubView.
    return AppDelegate.scene.keyWindow;
     */
    return AppDelegate.scene.windows.firstObject;
}

normally viewDidLoad shouldn't have anything related to layout, viewWillLayoutSubviews / viewDidLayoutSubviews is the proper place when you need final dimensions

Yep, I remember this from some of the code review hints you gave. Problem is, the app historically had (and still has) this is many places. If this ever becomes a bigger problem, this needs a lot of rework.

It's not required. The scene methods will simply be called on 13+ and the appdelegate ones - on 12.

Making this change while still support iOS 12 would be complicated from my point of view.

• The app would use two different ways for different iOS Version, which would need to be maintained.
• Several @available would need to be added, which would again removed once we are forced to raise the minimum version (isn't this anyway due soon?)

All methods that have a counterpart in scene must be implemented. (If they're implemented in the appdelegate of course)

Ok. This is not a problem. In the case we raise minimum version, we need to implement the methods only in SceneDelegate and remove them from AppDelegate, right?

[kambala-decapitator]

The app would use two different ways for different iOS Version, which would need to be maintained.

obviously :) But this is easy to tackle by extracting all the functionality in a separate method that'd be called by the 2 implementations.

Several @available would need to be added, which would again removed once we are forced to raise the minimum version (isn't this anyway due soon?)

is it a big deal to remove them? :) "soon" could be in some years, nobody knows. iOS 8/9 minimum has been around quite for some time for example.

In the case we raise minimum version, we need to implement the methods only in SceneDelegate and remove them from AppDelegate, right?

basically yes. Even if you don't remove them, they won't be called anyway. Just keep in mind that not all AD methods become obsolete - only those that relate to the app lifecycle and are available in UIScene API.

[wutschel]

obviously :) But this is easy to tackle by extracting all the functionality in a separate method that'd be called by the 2 implementations.

Sure, like done for the colors to support dark/light mode since years.

is it a big deal to remove them? :) "soon" could be in some years, nobody knows. iOS 8/9 minimum has been around quite for some time for example.

"Soon" I thought is most likely with next release? Wasn't it the case that ASC requests to use certain version, which automatically limit the support for minimum versions? In the last years I recall we had such moves coming in Q2 of the year.

basically yes. Even if you don't remove them, they won't be called anyway. Just keep in mind that not all AD methods become obsolete - only those that relate to the app lifecycle and are available in UIScene API.

Yep, only the methods which also exist in AppDelegate would be replaced. I already saw this is not the case for all of them.

[kambala-decapitator]

"Soon" I thought is most likely with next release? Wasn't it the case that ASC requests to use certain version, which automatically limit the support for minimum versions? In the last years I recall we had such moves coming in Q2 of the year.

ASC requires new iOS SDK (hence, new Xcode version) every year. But new iOS SDK / Xcode doesn't imply higher minimum deployment version automatically. Anyway, we'll see in a couple of weeks on WWDC.

[wutschel]

What happens to all the notifications like UIApplicationWillEnterForegroundNotification? They need to replace with UISceneWillEnterForegroundNotification and their likes? I am not sure about the Apple doc which seems to point to UIApplication notifications still being sent.