viewWillTransition not called since change to UISceneDelegate

I tested on a project with SceneDelegate.

    override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        
        super.viewWillTransition(to: size, with: coordinator)
        // Some stuff
        print(#function)
    }

viewWillTransition gets called when I rotate screen, as log shows:

viewWillTransition(to:with:)

Please show code of:

• SceneDelegate
• AppDelegate

and check you have correctly defined the SceneManifest in info.plist

Thanks for your reply!

This is our scene configuration:

	<dict>
		<key>UIApplicationSupportsMultipleScenes</key>
		<false/>
		<key>UISceneConfigurations</key>
		<dict>
			<key>UIWindowSceneSessionRoleApplication</key>
			<array>
				<dict>
					<key>UISceneConfigurationName</key>
					<string>Default Configuration</string>
					<key>UISceneDelegateClassName</key>
					<string>$(PRODUCT_MODULE_NAME).SceneDelegate</string>
				</dict>
				<dict>
					<key>UISceneConfigurationName</key>
					<string>Stub Configuration</string>
					<key>UISceneDelegateClassName</key>
					<string>$(PRODUCT_MODULE_NAME).StubSceneDelegate</string>
				</dict>
			</array>
		</dict>
	</dict>

This is from our AppDelegate:

        UISceneConfiguration(name: "Default Configuration", sessionRole: .windowApplication)
    }

And this from the SceneDelegate:

        guard let windowScene = scene as? UIWindowScene else { return }

        let window = UIWindow(windowScene: windowScene)
        window.rootViewController = TestViewController()
        self.window = window
        window.makeKeyAndVisible()

So I thinks this is very straightforward. It also works for me in another project without problems.

Not sure this matters, but when I compare to info.plist in a test project:

• I have an additional UISceneStoryboardFile : Main, after UISceneDelegateClassName
• You have 2 UISceneConfigurationName. Why ? I note that you have set UIApplicationSupportsMultipleScenes as false

AppDelegate is different as well:

    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        // Called when a new scene session is being created.
        // Use this method to select a configuration to create the new scene with.
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }

In which func is code of SceneDelegate ? Do you use a storyboard ?

For everyone who is interested in this problem, here ist the solution:

We didn’t implement the method application(_:didFinishLaunchingWithOptions:) inside our AppDelegate. This somehow caused the app to not call viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) inside our ViewControllers. After we changed our app to using a SceneDelegate we didn’t need the method in the AppDelegate anymore, so we removed it. It is also declared as optional in the documentation. So I think this should not have such an effect on the app, but at least it works now again.