iOS音频的后台播放总结（后台网络请求歌曲，Remote控制，锁屏封面，各种打断）

在没有网络的情况下，音频的后台播放比较简单，google一下可以搜到很多资料，但是如果每次歌曲的请求都是通过网络，就不成了，有时可以也扛不了几首，这里总结下实现方法，可以实现像电台一样的功能，后台播放，网络请求歌曲，Remote控制，锁屏有封面，电话和听歌打断处理等。

 

 

初始化AudioSession和基本配置

音频播放器采用的AVPlayer ，自己进行了功能封装，暂且不谈，在程序启动的时候需要配置AudioSession，AudioSession负责应用音频的设置，比如支不支持后台，打断等等，这一步很重要，比如在viewdidload里初始化AVplayer以后要调用下面的函数:

-(void)setAudioSession{//AudioSessionInitialize用于控制打断 ，后面会说AudioSessionInitialize (NULL,                          // ‘NULL’ to use the default (main) run loopNULL,                          // ‘NULL’ to use the default run loop modeASAudioSessionInterruptionListener,  // a reference to your interruption callbackNULL                       // data to pass to your interruption listener callback);//这种方式后台，可以连续播放非网络请求歌曲，遇到网络请求歌曲就废,需要后台申请taskAVAudioSession *session = [AVAudioSession sharedInstance];NSError *setCategoryError = nil;BOOL success = [session setCategory:AVAudioSessionCategoryPlayback error:&setCategoryError];if (!success){/* handle the error condition */return;}NSError *activationError = nil;success = [session setActive:YES error:&activationError];if (!success){/* handle the error condition */return;}}

AudioSessionInitialize用于处理中断处理，AVAudioSession主要调用setCategory和setActive方法来进行设置，AVAudioSessionCategoryPlayback一般用于支持后台播放，在官方文档可以看到其他的类型，每个分别适用于不同的场合：

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NSString *const <a href="file:///Users/lipengxuan/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.AppleiOS6.0.iOSLibrary.docset/Contents/Resources/Documents/documentation/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html#//apple_ref/doc/c_ref/AVAudioSessionCategoryAmbient">

<blockquote>AVAudioSessionCategoryAmbient</blockquote>

</a>;

NSString *const <a href="file:///Users/lipengxuan/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.AppleiOS6.0.iOSLibrary.docset/Contents/Resources/Documents/documentation/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html#//apple_ref/doc/c_ref/AVAudioSessionCategorySoloAmbient">

<blockquote>AVAudioSessionCategorySoloAmbient</blockquote>

</a>;

NSString *const <a href="file:///Users/lipengxuan/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.AppleiOS6.0.iOSLibrary.docset/Contents/Resources/Documents/documentation/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html#//apple_ref/doc/c_ref/AVAudioSessionCategoryPlayback">

<blockquote>AVAudioSessionCategoryPlayback</blockquote>

</a>;

NSString *const <a href="file:///Users/lipengxuan/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.AppleiOS6.0.iOSLibrary.docset/Contents/Resources/Documents/documentation/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html#//apple_ref/doc/c_ref/AVAudioSessionCategoryRecord">

<blockquote>AVAudioSessionCategoryRecord</blockquote>

</a>;

NSString *const <a href="file:///Users/lipengxuan/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.AppleiOS6.0.iOSLibrary.docset/Contents/Resources/Documents/documentation/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html#//apple_ref/doc/c_ref/AVAudioSessionCategoryPlayAndRecord">

<blockquote>AVAudioSessionCategoryPlayAndRecord</blockquote>

</a>;

NSString *const <a href="file:///Users/lipengxuan/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.AppleiOS6.0.iOSLibrary.docset/Contents/Resources/Documents/documentation/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html#//apple_ref/doc/c_ref/AVAudioSessionCategoryAudioProcessing">

<blockquote>AVAudioSessionCategoryAudioProcessing</blockquote>

</a>;

NSString *const <a href="file:///Users/lipengxuan/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.AppleiOS6.0.iOSLibrary.docset/Contents/Resources/Documents/documentation/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html#//apple_ref/doc/c_ref/AVAudioSessionCategoryMultiRoute">

<blockquote>AVAudioSessionCategoryMultiRoute</blockquote>

</a>;

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除了代码的初始化，很重要的一步是对info-plist的设置，让应用支持音频的后台播放

库的引入包括：

AudioToolBox.framework

MediaPlayer.framework

CoreMedia.framework

AVFoundation.framework

 

后台播放

正常情况下，如果配置了AVAudioSessionCategoryPlayback这个方法并修改了info-plist文件，应用就已经支持后台音频播放了，但是如果每一首歌曲都不存在本地，在网络的话就不行了，需要申请后台任务来进行处理,首先修改:

- (void)applicationDidEnterBackground:(UIApplication *)application {[application beginReceivingRemoteControlEvents];}

然后在播放器的播放函数里添加：

-(void)justPlay{UIBackgroundTaskIdentifier bgTask = 0; if([UIApplication sharedApplication].applicationState== UIApplicationStateBackground) {NSLog(@”xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx后台播放”);[thePlayer play];UIApplication*app = [UIApplication sharedApplication];UIBackgroundTaskIdentifier newTask = [app beginBackgroundTaskWithExpirationHandler:nil];if(bgTask!= UIBackgroundTaskInvalid) {[app endBackgroundTask: bgTask];}bgTask = newTask;}else {NSLog(@”xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx前台播放”);[thePlayer play];}}

这样播放就可以进行前台或者后台的判断，支持网络后台播放了，一首一首连续播放。

Remote控制

在播放视图的ViewController里加上这两个函数:

- (void)viewDidAppear:(BOOL)animated {NSLog(@”viewDidAppear!!!”);[super viewDidAppear:animated];//Once the view has loaded then we can register to begin recieving controls and we can become the first responder[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];[self becomeFirstResponder];}- (void)viewWillDisappear:(BOOL)animated {NSLog(@”viewWillDisappear!!!”);[super viewWillDisappear:animated];//End recieving events[[UIApplication sharedApplication] endReceivingRemoteControlEvents];[self resignFirstResponder];}

当然也可以同理放到delegate.m里面的进入后台和回到前台的函数中，否则的话，上面的代码只是允许当前视图的情况下进入后台可以Remote控制

 

然后添加下面的代码：

 

-(void)remoteControlReceivedWithEvent:(UIEvent *)event{//if it is a remote control event handle it correctlyif (event.type == UIEventTypeRemoteControl) {if (event.subtype == UIEventSubtypeRemoteControlTogglePlayPause) {[self playerTap];} else if (event.subtype == UIEventSubtypeRemoteControlNextTrack){[self nextSongAuto];[self configNowPlayingInfoCenter];}}}//Make sure we can recieve remote control events- (BOOL)canBecomeFirstResponder {return YES;}

锁屏封面

一般在每次切换歌曲或者更新信息的时候要调用这个方法

- (void)configNowPlayingInfoCenter {NSDictionary *albumDic=[currentParserSongArray objectAtIndex:songIndex];if (NSClassFromString(@”MPNowPlayingInfoCenter”)) {NSMutableDictionary * dict = [[NSMutableDictionary alloc] init];[dict setObject:[albumDic objectForKey:@"name"] forKey:MPMediaItemPropertyTitle];[dict setObject:[albumDic objectForKey:@"singer"] forKey:MPMediaItemPropertyArtist];[dict setObject:[albumDic objectForKey:@"album"] forKey:MPMediaItemPropertyAlbumTitle];MPMediaItemArtwork * mArt = [[MPMediaItemArtwork alloc] initWithImage:cdCoverImgView.image];[dict setObject:mArt forKey:MPMediaItemPropertyArtwork];[MPNowPlayingInfoCenter defaultCenter].nowPlayingInfo = nil;[[MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:dict];}} 

打断处理

试用了官方文档上的各种代理方法，打断通知，都没用，后来用C函数处理可以控制打断，首先AudioToolBox.framework是需要引入的

在设定session的时候调用了ASAudioSessionInterruptionListener这个函数 ，就是处理打断的，在所需加入的类的实现

@implementation前面加入这个静态方法

static void ASAudioSessionInterruptionListener(void *inClientData, UInt32 inInterruptionState){[[ToolManager defaultManager] handleInterruption:inInterruptionState];}

每次打断结束或者开始都会调用这个方法  ，inInterruptionState来判断是开始还是结束，因为是C函数，不可以直接调用类中[self  xxx]方法，通知也没用 ，故写了个单例类，接收这个参数，然后进行判断

- (void)handleInterruptionChangeToState:(NSNotification *)notification{AudioQueuePropertyID inInterruptionState=[[notification object] longValue]; if (inInterruptionState == kAudioSessionBeginInterruption){NSLog(@”begin interruption——->”);}else if (inInterruptionState == kAudioSessionEndInterruption){NSLog(@”end interruption——->”); }}