iOS:开始从后台播放声音
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【中文标题】iOS:开始从后台播放声音【英文标题】:iOS: Start playing sound from background 【发布时间】:2015-06-28 16:51:04 【问题描述】:当用户关闭应用程序时,我需要开始播放声音。我使用applicationDidEnterBackground
方法。这里是:
func applicationDidEnterBackground(application: UIApplication)
let dispatchQueue =
dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
dispatch_async(dispatchQueue, [weak self] in
var audiosessionError: NSError?
let audioSession = AVAudioSession.sharedInstance()
NSNotificationCenter.defaultCenter().addObserver(self!,
selector: "handleInterruption:",
name: AVAudioSessionInterruptionNotification,
object: nil)
audioSession.setActive(true, error: nil)
if audioSession.setCategory(AVAudioSessionCategoryPlayback,
error: &audioSessionError)
println("Successfully set the audio session")
else
println("Could not set the audio session")
let filePath = NSBundle.mainBundle().pathForResource("MySong",
ofType:"mp3")
let fileData = NSData(contentsOfFile: filePath!,
options: .DataReadingMappedIfSafe,
error: nil)
var error:NSError?
/* Start the audio player */
self!.audioPlayer = AVAudioPlayer(data: fileData, error: &error)
/* Did we get an instance of AVAudioPlayer? */
if let theAudioPlayer = self!.audioPlayer
theAudioPlayer.delegate = self;
if theAudioPlayer.prepareToPlay() &&
theAudioPlayer.play()
println("Successfully started playing")
else
println("Failed to play")
else
/* Handle the failure of instantiating the audio player */
)
func handleInterruption(notification: NSNotification)
/* Audio Session is interrupted. The player will be paused here */
let interruptionTypeAsObject =
notification.userInfo![AVAudioSessionInterruptionTypeKey] as! NSNumber
let interruptionType = AVAudioSessionInterruptionType(rawValue:
interruptionTypeAsObject.unsignedLongValue)
if let type = interruptionType
if type == .Ended
/* resume the audio if needed */
func audioPlayerDidFinishPlaying(播放器: AVAudioPlayer!, 成功标记:Bool)
println("Finished playing the song")
/* The flag parameter tells us if the playback was successfully
finished or not */
if player == audioPlayer
audioPlayer = nil
它不起作用。调试后我看到theAudioPlayer.play()
返回false
。例如,如果我在applicationDidFinishLaunching
中运行此代码,它会播放声音。我在我的Info.plist
中添加了后台模式App plays audio or streams audio/video using AirPlay
,这里有什么问题?
【问题讨论】:
你需要一个 UIBackgroundTaskIdentifier 好的,请举个例子。 查看我用 Swift 示例更新的答案。 @Woodstock 此代码来自那里。 【参考方案1】:在非常基本的层面上,您的应用要在后台播放音频应满足三个先决条件:
必须播放音乐在目标功能中为音频设置“背景模式”。
对于基本播放,初始化您的音频会话,并将您的音频会话类别设置为 AVAudioSessionCategoryPlayback。否则,您将获得默认行为。
您还应该配置您的应用以响应
音频输出的变化 音频会话中断(例如电话) 远程控制事件(通过控制中心或锁定屏幕)查看this Swift 示例。
【讨论】:
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