iOS开源项目：AudioPlayer

AudioPlayer是一个基于AVAudioStreamer的在线音乐播放软件。

https://github.com/marshluca/AudioPlayer

首先将歌曲信息存储在NSArray中：

    itemArray = [[NSArray arrayWithObjects:
                  [NSDictionary dictionaryWithObjectsAndKeys:@"温柔", @"song", @"五月天", @"artise", @"http://y1.eoews.com/assets/ringtones/2012/5/18/34049/oiuxsvnbtxks7a0tg6xpdo66exdhi8h0bplp7twp.mp3", @"url", nil],
                  [NSDictionary dictionaryWithObjectsAndKeys:@"今天", @"song", @"刘德华", @"artise", @"http://y1.eoews.com/assets/ringtones/2012/5/18/34045/hi4dwfmrxm2citwjcc5841z3tiqaeeoczhbtfoex.mp3", @"url", nil],
                  [NSDictionary dictionaryWithObjectsAndKeys:@"K歌之王", @"song", @"陈奕迅", @"artise", @"http://y1.eoews.com/assets/ringtones/2012/5/17/34031/axiddhql6nhaegcofs4hgsjrllrcbrf175oyjuv0.mp3", @"url", nil],
                  [NSDictionary dictionaryWithObjectsAndKeys:@"知足", @"song", @"五月天", @"artise", @"http://y1.eoews.com/assets/ringtones/2012/5/17/34016/eeemlurxuizy6nltxf2u1yris3kpvdokwhddmeb0.mp3", @"url", nil],
                  [NSDictionary dictionaryWithObjectsAndKeys:@"桔子香水", @"song", @"任贤齐", @"artise", @"http://y1.eoews.com/assets/ringtones/2012/6/29/36195/mx8an3zgp2k4s5aywkr7wkqtqj0dh1vxcvii287a.mp3", @"url", nil],

                 nil] retain];

然后在播放的时候：

- (void)playAudio:(AudioButton *)button
{
    NSInteger index = button.tag;
    NSDictionary *item = [itemArray objectAtIndex:index];

    if (_audioPlayer == nil) {
        _audioPlayer = [[AudioPlayer alloc] init];
    }

    if ([_audioPlayer.button isEqual:button]) {
        [_audioPlayer play];
    } else {
        [_audioPlayer stop];

        _audioPlayer.button = button;
        _audioPlayer.url = [NSURL URLWithString:[item objectForKey:@"url"]];

        [_audioPlayer play];
    }
}

在[_audioPlayer play]内部，使歌曲的url初始化AudioStreamer，并用NSTimer设置一个每0.1秒调用一次的方法来更新歌曲的播放进度。然后注册一个播放状态变化的通知。

- (void)play
{
    if (!streamer) {

        self.streamer = [[AudioStreamer alloc] initWithURL:self.url];

        // set up display updater
        NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:
                                    [self methodSignatureForSelector:@selector(updateProgress)]];
        [invocation setSelector:@selector(updateProgress)];
        [invocation setTarget:self];

        timer = [NSTimer scheduledTimerWithTimeInterval:0.1
                                             invocation:invocation
                                                repeats:YES];

        // register the streamer on notification
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(playbackStateChanged:)
                                                     name:ASStatusChangedNotification
                                                   object:streamer];
    }

    if ([streamer isPlaying]) {
        [streamer pause];
    } else {
        [streamer start];
    }
}