MPMusicPlayerController队列问题

Question

我的MPMusicPlayerController出了点问题。这是一个iPodMusicPlayer，不是一个应用音乐播放器。我的问题是我不能让队列按正确的顺序播放。让我进一步解释一下：

我使用iPod选取器选择一个媒体收藏，然后将其添加到音乐播放器的队列中。完成此操作后，我将在表视图上显示集合中的项。然后，用户可以“玩”这个队列。然而，由于某些原因，当我尝试使用ipod控件浏览播放列表时，队列似乎排列不正确。下面是一些代码：

媒体选取器调用此方法：

-(void)updatePlayerQueueWithMediaCollection:(MPMediaItemCollection *)collection {

if (collection) {

    // If there's no playback queue yet...

    if (self.userMediaItemCollection == nil) {
        [self setUserMediaItemCollection: collection];
        [self.musicPlayer setQueueWithItemCollection:self.userMediaItemCollection];
    } else {
        BOOL wasPlaying = NO;
        if (self.musicPlayer.playbackState == MPMusicPlaybackStatePlaying) {
            wasPlaying = YES;
        }

        // Save the now-playing item and its current playback time.

        MPMediaItem *nowPlayingItem        = self.musicPlayer.nowPlayingItem;
        NSTimeInterval currentPlaybackTime = self.musicPlayer.currentPlaybackTime;

        // Combine the previously-existing media item collection with the new one

        NSMutableArray *combinedMediaItems =
        [[self.userMediaItemCollection items] mutableCopy];
        NSArray *newMediaItems = [collection items];
        [combinedMediaItems addObjectsFromArray: newMediaItems];

        [self setUserMediaItemCollection:[MPMediaItemCollection collectionWithItems:(NSArray *) combinedMediaItems]];

        [self.musicPlayer setQueueWithItemCollection: self.userMediaItemCollection];

        // Restore the now-playing item and its current playback time.

        self.musicPlayer.nowPlayingItem      = nowPlayingItem;
        self.musicPlayer.currentPlaybackTime = currentPlaybackTime;

        if (wasPlaying) {
            [self.musicPlayer play];
        }
    }
}
int i = 0; 
for (MPMediaItem *item in [self.userMediaItemCollection items]){
    NSLog(@"playback queue item %i has title %@",i, [item valueForKey:MPMediaItemPropertyTitle] );
    i++;
}

}

很简单，这是直接从苹果获取的。底部的NSLog注销队列，它看起来是正确的。

从这里，用户可以单击播放按钮来播放队列。我是这样设置的：

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];

if ([segue.destinationViewController respondsToSelector:@selector(setNowPlayingItem:)]) {
    NSArray *items = [[MusicPlayerManager sharedMusicPlayer].userMediaItemCollection items];
    [segue.destinationViewController performSelector:@selector(setNowPlayingItem:) withObject:[items objectAtIndex:indexPath.row]];
}

if ([segue.destinationViewController respondsToSelector:@selector(setTrackList:)]) {
    [segue.destinationViewController performSelector:@selector(setTrackList:) withObject:[MusicPlayerManager sharedMusicPlayer].userMediaItemCollection];
    NSLog(@"tracklist from tltbvc looks like %@", [MusicPlayerManager sharedMusicPlayer].userMediaItemCollection);
}

}

在目标视图控制器中，setNowPlayingItem方法如下所示：

-(void) setNowPlayingItem:(MPMediaItem *)nowPlayingItem {
    _nowPlayingItem = nowPlayingItem;
    [MusicPlayerManager sharedMusicPlayer].musicPlayer.nowPlayingItem = nowPlayingItem;
    [[MusicPlayerManager sharedMusicPlayer].musicPlayer play];
    NSLog(@"index of now playing item %i", [[MusicPlayerManager sharedMusicPlayer].musicPlayer indexOfNowPlayingItem]);
}

这将从tableview indexpath中播放正确的歌曲，但由于某些原因，索引不再与其在表中的位置相匹配。如果行索引0中的歌曲是ABC，则播放器播放ABC，但注销不再为0的indexOfNowPlayingItem。当我尝试向前和向后跳转时，队列中的顺序不再保持。我不知道发生了什么

非常感谢您的帮助，很抱歉包含这么多代码

Answer 1

哇，出于某种原因，它的随机播放设置为开。这太尴尬了。这解决了所有问题：

    sharedMusicPlayer.musicPlayer.shuffleMode = MPMusicShuffleModeOff;