当用户关闭应用时,我需要开始播放声音。我使用 applicationDidEnterBackground
方法。以下是代码:
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 */
}
}
}
音频播放器完成播放时,使用以下函数:
func audioPlayerDidFinishPlaying(player: AVAudioPlayer!, successfully flag: Bool){
println("Finished playing the song")
/* The flag parameter tells us if the playback was successfully
finished or not */
if player == audioPlayer{
audioPlayer = nil
}
}
它无法正常工作。经过调试后,我发现theAudioPlayer.play()
返回false
。如果我例如在applicationDidFinishLaunching
中运行此代码,它会播放声音。我在Info.plist
中添加了后台模式App plays audio or streams audio/video using AirPlay
。这里出了什么问题?