How to receive NSNotifications from UIWebView embedded YouTube video playback

I didn't received any notifications for MPMoviePlayerController. What am I doing wrong?

I use following logic.

I'm begining to play youtube video in UIWebView. UIWebView calls a standard MPMoviePlayerController. I don't control MPMoviePlayerController because I didn't instantiate MPMoviePlayerController.

I run youtube's clip with autoplay (1 second delay):

[self performSelector:@selector(touchInView:) withObject:b afterDelay:1];

My code is:

- (void)viewDidLoad
{
    [super viewDidLoad];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(loadStateDidChange:) name:MPMoviePlayerLoadStateDidChangeNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playbackDidFinish:) name:MPMoviePlayerDidExitFullscreenNotification object:nil];

    [self embedYouTube];
}

- (void)loadStateDidChange:(NSNotification*)notification
{
    NSLog(@"________loadStateDidChange");
}

- (void)playbackDidFinish:(NSNotification*)notification
{
    NSLog(@"________DidExitFullscreenNotification");
}

- (void)embedYouTube
{
    CGRect frame = CGRectMake(25, 89, 161, 121);
    NSString *urlString = [NSString stringWithString:@"http://www.youtube.com/watch?v=sh29Pm1Rrc0"];

    NSString *embedHTML = @"<html><head>\
    <body style=\"margin:0\">\
    <embed id=\"yt\" src=\"%@\" type=\"application/x-shockwave-flash\" \
    width=\"%0.0f\" height=\"%0.0f\"></embed>\
    </body></html>";
    NSString *html = [NSString stringWithFormat:embedHTML, urlString, frame.size.width, frame.size.height];
    UIWebView *videoView = [[UIWebView alloc] initWithFrame:frame];
    videoView.delegate = self;

    for (id subview in videoView.subviews)
        if ([[subview class] isSubclassOfClass: [UIScrollView class]])
            ((UIScrollView *)subview).bounces = NO;

            [videoView loadHTMLString:html baseURL:nil];
    [self.view addSubview:videoView];
    [videoView release];
}

- (void)webViewDidFinishLoad:(UIWebView *)_webView 
{
    UIButton *b = [self findButtonInView:_webView];
    [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(touchInView:) object:b];
    [self performSelector:@selector(touchInView:) withObject:b afterDelay:1];
}

- (UIButton *)findButtonInView:(UIView *)view 
{
    UIButton *button = nil;

    if ([view isMemberOfClass:[UIButton class]]) {
        return (UIButton *)view;
    }

    if (view.subviews && [view.subviews count] > 0) 
    {
        for (UIView *subview in view.subviews) 
        {
            button = [self findButtonInView:subview];
            if (button) return button;
        }
    }
    return button;
}

- (void)touchInView:(UIButton*)b
{
    [b sendActionsForControlEvents:UIControlEventTouchUpInside];
}

UPDATE: I'm creating application that plays youtube's video. You can run playlist and you will see first video. When first video has ended, second video begins play automatically and so on.

I need to support ios 4.1 and above.

UPDATE2: @H2CO3 I'm trying to use your url-scheme, but it don't works. Delegate method didn't called on exit event. I added my html url to log. It is:

<html><head>    <body style="margin:0">    
<script>function endMovie() 
{document.location.href="somefakeurlscheme://video-ended";} 
 </script>      <embed id="yt" src="http://www.youtube.com/watch?v=sh29Pm1Rrc0"        
 onended="endMovie()" type="application/x-shockwave-flash"  
 width="161" height="121"></embed>  
 </body></html>

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
  if ([[[request URL] absoluteString] hasPrefix:@"somefakeurlscheme://video-ended"]) 
  {
    [self someMethodSupposedToDetectVideoEndedEvent];
    return NO; // prevent really loading the URL
   }
  return YES; // else load the URL as desired
}

UPDATE3 @Till, I cann't caught UIMoviePlayerControllerDidExitFullscreenNotification, but I found MPAVControllerItemPlaybackDidEndNotification. MPAVControllerItemPlaybackDidEndNotification appears when playback video is ended.

But I don't understand how do I catch onDone notifications?


There are no documented notifications sent by the UIWebView embedded movie player.

In fact, the closed implementation used within the UIWebView does differ from the public MPMoviePlayerController in many aspects (e.g. DRM).

The most important classes used for playing video content within that UIWebView are called MPAVController and UIMoviePlayerController. The latter one makes the player appear like the MPMoviePlayerController fullscreen interface.

In case you dare to risk a rejection by Apple, there are actually ways to still achieve what you are looking for.

NOTE This is not documented and is subject to break on each and every new iOS release. It does however work on iOS4.3, 5.0 and 5.01, 5.1 and 6.0 and it may work on other versions as well.

I am not able to test this solution on iOS 4.1 and 4.2, so that is up to you to do. I highly suspect that it will work.


Fullscreen State

If, for example you are intending to react upon the user tapping the DONE button, you may be able to do it this way:

UPDATE The old version of this answer recommended to use UIMoviePlayerControllerDidExitFullscreenNotification whereas this new version (updated for iOS6) recommends using UIMoviePlayerControllerWillExitFullscreenNotification.

C-Language Level:

void PlayerWillExitFullscreen (CFNotificationCenterRef center,
                 void *observer,
                 CFStringRef name,
                 const void *object,
                 CFDictionaryRef userInfo)
{
    //do something...
}

CFNotificationCenterAddObserver(CFNotificationCenterGetLocalCenter(), 
    NULL, 
    PlayerWillExitFullscreen, 
    CFSTR("UIMoviePlayerControllerWillExitFullscreenNotification"), 
    NULL,  
    CFNotificationSuspensionBehaviorDeliverImmediately);

Objective-C Level:

- (void)playerWillExitFullscreen:(NSNotification *)notification
{
    //do something...
}

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

I did draft both, C-Level and Objective-C-Level options because the best way to actually find out about all of this is to use C-Level (CoreFoundation) functions as shown at the end of my answer. If the sender of a notification does not use Objective-C (NSNotifications), you may actually not be able to trap them using the NSNotification-mechanics.


Playback State

For examining the playback state, look out for "MPAVControllerPlaybackStateChangedNotification" (as drafted above) and examine the userInfo which may look like this:

{
    MPAVControllerNewStateParameter = 1;
    MPAVControllerOldStateParameter = 2;
}

Further Reverse Engineering

For reverse engineering and exploring all the notifications sent, use the following snippet.

void MyCallBack (CFNotificationCenterRef center,
                 void *observer,
                 CFStringRef name,
                 const void *object,
                 CFDictionaryRef userInfo)
{
    NSLog(@"name: %@", name);
    NSLog(@"userinfo: %@", userInfo);
}

CFNotificationCenterAddObserver(CFNotificationCenterGetLocalCenter(), 
    NULL, 
    MyCallBack, 
    NULL, 
    NULL,  
    CFNotificationSuspensionBehaviorDeliverImmediately);

In iOS 4.3+ you can use the UIMoviePlayerControllerDidEnterFullscreenNotification and UIMoviePlayerControllerDidExitFullscreenNotification notifications:

-(void)viewDidLoad
{

    ...

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(youTubeStarted:) name:@"UIMoviePlayerControllerDidEnterFullscreenNotification" object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(youTubeFinished:) name:@"UIMoviePlayerControllerDidExitFullscreenNotification" object:nil];
}

-(void)youTubeStarted:(NSNotification *)notification{
    // your code here
}

-(void)youTubeFinished:(NSNotification *)notification{
    // your code here
}