Wednesday, July 29, 2009
iPhone: MPMusicPlayerController: currentPlaybackTime and playbackDuration
Wednesday, July 29, 2009 
I started playing around with the iPhone MPMusicPlayerController and found that getting and displaying a track's duration is pretty simple, displaying the current time of the track wasn't so easy. I was expecting to find a notification of some kind akin to IsPlaying or something like that so that I didn't need to fire my own NSTimer.
Well, there doesn't seem to be one, we have access to MPMusicPlayerControllerNowPlayingItemDidChangeNotification, MPMusicPlayerControllerPlaybackStateDidChangeNotification, and MPMusicPlayerControllerVolumeDidChangeNotification. How do you like those constants? Verbose to say the least.
Anyway, I found that I had to run my own Timer, and I just started it up within viewDidLoad - every 0.5 seconds, almost like an onEnterFrame in Flash. In the end my code looks something like this... this may save you some time. The labels are IBOutlet objects, etc.
Well, there doesn't seem to be one, we have access to MPMusicPlayerControllerNowPlayingItemDidChangeNotification, MPMusicPlayerControllerPlaybackStateDidChangeNotification, and MPMusicPlayerControllerVolumeDidChangeNotification. How do you like those constants? Verbose to say the least.
Anyway, I found that I had to run my own Timer, and I just started it up within viewDidLoad - every 0.5 seconds, almost like an onEnterFrame in Flash. In the end my code looks something like this... this may save you some time. The labels are IBOutlet objects, etc.
- (void)onTimer:(NSTimer *)timer {
long currentPlaybackTime = self.musicPlayer.currentPlaybackTime;
int currentHours = (currentPlaybackTime / 3600);
int currentMinutes = ((currentPlaybackTime / 60) - currentHours*60);
int currentSeconds = (currentPlaybackTime % 60);
self.currentLabel.text = [NSString stringWithFormat:@"%i:%02d:%02d", currentHours, currentMinutes, currentSeconds];
}
- (void)viewDidLoad {
[super viewDidLoad];
self.musicPlayer = [MPMusicPlayerController iPodMusicPlayer];
// Initial sync of display with music player state
[self handleNowPlayingItemChanged:nil];
[self handlePlaybackStateChanged:nil];
[self handleExternalVolumeChanged:nil];
// Register for music player notifications
NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
[notificationCenter addObserver:self
selector:@selector(handleNowPlayingItemChanged:)
name:MPMusicPlayerControllerNowPlayingItemDidChangeNotification
object:self.musicPlayer];
[notificationCenter addObserver:self
selector:@selector(handlePlaybackStateChanged:)
name:MPMusicPlayerControllerPlaybackStateDidChangeNotification
object:self.musicPlayer];
[notificationCenter addObserver:self
selector:@selector(handleExternalVolumeChanged:)
name:MPMusicPlayerControllerVolumeDidChangeNotification
object:self.musicPlayer];
[self.musicPlayer beginGeneratingPlaybackNotifications];
currentTimer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(onTimer:) userInfo:nil repeats:YES];
}
- (void)handleNowPlayingItemChanged:(id)notification {
MPMediaItem *currentItem = self.musicPlayer.nowPlayingItem;
self.songLabel.text = [currentItem valueForProperty:MPMediaItemPropertyTitle];
self.artistLabel.text = [currentItem valueForProperty:MPMediaItemPropertyArtist];
self.albumLabel.text = [currentItem valueForProperty:MPMediaItemPropertyAlbumTitle];
// Current Playback Value - via the running timer
// The total duration of the track...
long totalPlaybackTime = [[[musicPlayer nowPlayingItem] valueForProperty: @"playbackDuration"] longValue];
int tHours = (totalPlaybackTime / 3600);
int tMins = ((totalPlaybackTime/60) - tHours*60);
int tSecs = (totalPlaybackTime % 60 );
self.durationLabel.text = [NSString stringWithFormat:@"%i:%02d:%02d", tHours, tMins, tSecs ];
// Display album artwork. self.artworkImageView is a UIImageView.
CGSize artworkImageViewSize = self.artworkImageView.bounds.size;
MPMediaItemArtwork *artwork = [currentItem valueForProperty:MPMediaItemPropertyArtwork];
if (artwork != nil) {
self.artworkImageView.image = [artwork imageWithSize:artworkImageViewSize];
} else {
self.artworkImageView.image = nil;
}
}Labels: iPhone
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