ios开发之MPNowPlayingInfoCenter 锁屏显示正在播放的音乐

今天在床上玩唱吧,听着歌锁屏了,当点亮屏幕的时候,锁屏页面出现了我正在听得歌曲 壁纸也换成了唱吧里面的歌手图片.做ios好几年了,从没有做过这个需求 于是好奇就翻看ios的API文档找到了这个类.

如下图

MPNowPlayingInfoCenter 解释

即时播放中心能够用于播放APP中正在播放的媒体信息.
播放的信息会显示在锁屏页面和多任务管理页面.如果用户是用airplay播放的话 会自动投射到相应的设备上.

下载源码

开始动手

让App支持后台运行

先创建工程,因为是audio 类型的app 需要支持后台播放 所以得要在plist 中声明属性.
添加如下属性

Required background modes -> App plays audio
如下图

添加播放的Frame

1. AVFoundation.framework
2. MediaPlayer.framework

开始代码吧

首先创建一个ViewController 和一个用于播放的按钮 playButton

@interface ViewController : UIViewController {

IBOutlet UIButton *playButton;

}

@property (nonatomic, retain) IBOutlet UIButton *playButton;

-(IBAction)playButtonPress:(id)sender;

加入播放用的控件audioPlayer 和其相应的头文件

#import <MediaPlayer/MPNowPlayingInfoCenter.h>
#import <MediaPlayer/MPMediaItem.h>
#import <AVFoundation/AVFoundation.h>
MPMoviePlayerController *audioPlayer;

@property (nonatomic, retain) MPMoviePlayerController *audioPlayer;

@synthesize playButton, audioPlayer;

在viewDidLoad 中 我们要把AudioPlayer 进行初始化 此处加载网络上的一首音频

[[AVAudioSession sharedInstance] setDelegate: self];

NSError *myErr;

// Initialize the AVAudioSession here.
if (![[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&myErr]) {
    // Handle the error here.
    NSLog(@"Audio Session error %@, %@", myErr, [myErr userInfo]);
}
else{
    // Since there were no errors initializing the session, we'll allow begin receiving remote control events
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
}

    //initialize our audio player
    audioPlayer = [[MPMoviePlayerController alloc] initWithContentURL:[NSURL URLWithString:@"http://www.cocoanetics.com/files/Cocoanetics_031.mp3"]];

    [audioPlayer setShouldAutoplay:NO];
    [audioPlayer setControlStyle: MPMovieControlStyleEmbedded];
    audioPlayer.view.hidden = YES;

    [audioPlayer prepareToPlay];

点击按钮开始播放,注意因为MPNowPlayingInfoCenter只支持5.0+ 所以为了防止低版本使用 巧妙的应用了NSClassFromString进行了判断

- (IBAction)playButtonPress:(id)sender {

    [audioPlayer play];

    Class playingInfoCenter = NSClassFromString(@"MPNowPlayingInfoCenter");

    if (playingInfoCenter) {


        NSMutableDictionary *songInfo = [ [NSMutableDictionary alloc] init];


        MPMediaItemArtwork *albumArt = [ [MPMediaItemArtwork alloc] initWithImage: [UIImage imagedNamed:@"AlbumArt"] ];

        [ songInfo setObject: @"Audio Title" forKey:MPMediaItemPropertyTitle ];
        [ songInfo setObject: @"Audio Author" forKey:MPMediaItemPropertyArtist ];
        [ songInfo setObject: @"Audio Album" forKey:MPMediaItemPropertyAlbumTitle ];
        [ songInfo setObject: albumArt forKey:MPMediaItemPropertyArtwork ];
        [ [MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:songInfo ];
    }
}

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参考http://jaysonlane.net/tech-blog/2012/04/lock-screen-now-playing-with-mpnowplayinginfocenter/