Detect when a webview video becomes fullscreen on ios8

问题

I have an app where users can open videos from UIWebview, including Youtube ones. In iOS7, I was able to get a notification when it started playing, or when it became full screen, which is vital for me to show certain options to the user and modify the interface.

I used to use this:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(VideoExitFullScreen:) name:@"UIMoviePlayerControllerDidExitFullscreenNotification" object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(VideoEnterFullScreen:) name:@"UIMoviePlayerControllerDidEnterFullscreenNotification" object:nil];

However, since iOS8, I can't achieve this. It is like the notification is no longer triggered from UIWebview videos. However, it is still triggered from normal videos, non-Webview, as I've tested.

Any idea of what have changed?

回答1:

This is the work around I found for this..

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(VideoExitFullScreen:)
                                                 name:UIWindowDidBecomeVisibleNotification
                                               object:self.view.window];

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(VideoEnterFullScreen:)
                                                 name:UIWindowDidBecomeHiddenNotification
                                               object:self.view.window];

回答2:

Swift 5.1:

NotificationCenter.default.addObserver(
    forName: UIWindow.didResignKeyNotification,
    object: self.view.window,
    queue: nil
) { notification in
    print("Video is now fullscreen")
}

NotificationCenter.default.addObserver(
    forName: UIWindow.didBecomeKeyNotification,
    object: self.view.window,
    queue: nil
) { notification in
    print("Video stopped")
}

回答3:

update for Swift 4.2, iOS 12.1 and WKWebView:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    // listen for videos playing in fullscreen
    NotificationCenter.default.addObserver(self, selector: #selector(onDidEnterFullscreen(_:)), name: UIWindow.didBecomeVisibleNotification, object: view.window)

    // listen for videos stopping to play in fullscreen
    NotificationCenter.default.addObserver(self, selector: #selector(onDidLeaveFullscreen(_:)), name: UIWindow.didBecomeHiddenNotification, object: view.window)
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)

    // remove video listeners
    NotificationCenter.default.removeObserver(self, name: UIWindow.didBecomeVisibleNotification, object: view.window)
    NotificationCenter.default.removeObserver(self, name: UIWindow.didBecomeHiddenNotification, object: view.window)
}

@objc func onDidEnterFullscreen(_ notification: Notification) {
    print("video is now playing in fullscreen")
}

@objc func onDidLeaveFullscreen(_ notification: Notification) {
    print("video has stopped playing in fullscreen")
}

回答4:

@NorthBlast's answer works well for detecting any UIWindow appearing on top of the UIViewController that holds the UIWebView. Unfortunately, it's hard to filter what kind of UIWindow is (since, well... you can't really know if it is a video or some other kind of window).

There are 3 special cases I prefer to filter, in which you're sure they are NOT video player windows, those are:

1) _UIAlertControllerShimPresenterWindow, which is a kind of window that appears when using alerts (like UIAlertView).

2) UITextEffectsWindow, which appears when presenting special iOS windows (like the share window, UIActivityViewController).

3) UIRemoteKeyboardWindow which appears when presenting the keyboard (for some reason, this class only appeared to me when using Swift, but on Objective-C it didn't... no clue why is that).

So to subscribe to notifications, I use (just like @NorthBlast said):

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(windowDidBecomeActive:)
                                             name:UIWindowDidBecomeVisibleNotification
                                           object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(windowDidBecomeHidden:)
                                             name:UIWindowDidBecomeHiddenNotification
                                           object:nil];

Then the implementations:

- (void)windowDidBecomeActive:(NSNotification *)notification {
    if ( [self isVideoPlayerWindow:notification.object] ) {
        // Do what's needed if it is a video
        // For example, on a live streaming radio app, I would stop the audio if a video is started
    }
}

- (void)windowDidBecomeHidden:(NSNotification *)notification {
    if ( [self isVideoPlayerWindow:notification.object] ) {
        // Do what's needed if it is a video
    }
}

- (BOOL)isVideoPlayerWindow:(id)notificationObject {
    /*
     Define non video classes here, add more if you need it
    */
    static NSArray *nonVideoClasses = @[
        @"_UIAlertControllerShimPresenterWindow",
        @"UITextEffectsWindow",
        @"UIRemoteKeyboardWindow"
    ];

    BOOL isVideo = YES;
    for ( NSString *testClass in nonVideoClasses ) {
        isVideo = isVideo && ! [notificationObject isKindOfClass:NSClassFromString(testClass)];
    }

    return isVideo;
}