AVQueuePlayer/AVPlayer loading notification?

Question

I have an AVQueuePlayer (which obviously extends AVPlayer) that loads a playlist of streaming audio. Streaming is all working fine, but I'd like to have an activity indicator to show the user audio is loading. Trouble is, I can't seem to find any such Notification in AVQueuePlayer (or AVPlayer) that would indicate when the audio buffer has finished loading/is ready to play (nor does there appear to be a delegate method). Any thoughts?

Solution

You will have to use KVO to get this done.

For each item you are adding to the queue, you may setup observers like this:

item_ = [[AVPlayerItem playerItemWithURL:[NSURL URLWithString:@"http://somefunkyurl"]] retain];
[item_ addObserver:self forKeyPath:@"status" options:0 context:nil];
[item_ addObserver:self forKeyPath:@"playbackBufferEmpty" options:0 context:nil];

Now you can evaluate the status of that item within the observer method;

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if ([object isKindOfClass:[AVPlayerItem class]])
    {
        AVPlayerItem *item = (AVPlayerItem *)object;
        //playerItem status value changed?
        if ([keyPath isEqualToString:@"status"])
        {   //yes->check it...
            switch(item.status)
            {
                case AVPlayerItemStatusFailed:
                    NSLog(@"player item status failed");
                break;
                case AVPlayerItemStatusReadyToPlay:
                    NSLog(@"player item status is ready to play");
                break;
                case AVPlayerItemStatusUnknown:
                    NSLog(@"player item status is unknown");
                break;
            }
        }
        else if ([keyPath isEqualToString:@"playbackBufferEmpty"])
        {
            if (item.playbackBufferEmpty)
            {
                NSLog(@"player item playback buffer is empty");
            }
        }
    }
}

Comments

[reddersky]

You can also observe the playbackBufferEmpty property of the AVPlayerItem objects to detect if/when your buffer empties during playback so that you can show an activity indicator or 'buffering' warning.

[reddersky]

You could always up my comment if you liked it ;-)

[danyowdee]

Minor remark: You should use the context to discern how to handle a KVO notification! It probably won't matter if you're subclassing NSObject but as soon as you're subclassing something a little more advanced than that, not forwarding observeValueForKeyPath:... can lead to the most peculiar side-effects.

[mostafa tourad]

@danyowdee you are so right - this really is just for the sake of the of this example. I shall never ever use the key path for checking if my observer is invoked for an event I actually intend to register. Using the context certainly is quicker and more reliable.

[jose920405]

Best way for remove this observer?

[Mohammad Zaid Pathan]

@Till , when should we stopAnimating our activity indicator?

[mostafa tourad]

@ZaidPathan you should start animating initially and whenever you got a playbackBufferEmpty and stop animating as soon as you get a status change.

[Gabriel.Massana]

@reddersky / Till to detect when the buffer is empty you can also use AVPlayerItemPlaybackStalledNotification notification