MPMusicPlayer的播放状态给出了错误的状态

Question

我的应用就像iPhone中的默认iPod播放器一样。

- ＆GT;它将获得iPod音乐播放器的所有播放列表，艺术家，专辑和歌曲。 - ＆GT;它在低于ios 5.0的情况下运行良好，但是当达到5.0或更高时，我会得到错误的播放状态（有时）。请帮我。

- ＆GT;当我从歌曲列表中选择歌曲时，这是我的代码，mediaItemCollection包含songslist，indexofcurrentObject是歌曲编号

- (void)updatePlayerQueueWithMediaCollection:(MPMediaItemCollection *)mediaItemCollection currentIndex:(int)indexOfCurrentObject

{

[musicPlayer stop];
if (userMediaItemCollection)
{
userMediaItemCollection=nil; 
}
musicPlayer.nowPlayingItem=nil;

userMediaItemCollection=[MPMediaItemCollection collectionWithItems:[mediaItemCollection items]];

[musicPlayer setQueueWithItemCollection:userMediaItemCollection];
[musicPlayer setNowPlayingItem:[[userMediaItemCollection items]objectAtIndex:indexOfCurrentObject]];
[self enablePrevAndNextButtons];

[musicPlayer play];        

}

-(void)playbackStateDidChanged:(NSNotification *)notification

{

if (musicPlayer.playbackState!=MPMusicPlaybackStatePlaying)
{
    [playPauseButton setBackgroundImage:[UIImage imageNamed:@"play_iPad.png"] forState:UIControlStateNormal];
}
else if(musicPlayer.playbackState==MPMusicPlaybackStatePlaying)
{
    [playPauseButton setBackgroundImage:[UIImage imageNamed:@"pause_iPad.png"] forState:UIControlStateNormal];
}

}