iOS音频的后台播放总结

 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 loop

NULL,                          // ‘NULL’ to use the default run loop mode

ASAudioSessionInterruptionListener,  // a reference to your interruption callback

NULL                       // 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task

AVAudioSession *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：

 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

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]] > ;

 

1

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 correctly

if (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——->”);

}

}