AVAudioPlayer not playing audio in Swift

Question

I have this code in a very simple, single view Swift application in my ViewController:

var audioPlayer = AVAudioPlayer()

@IBAction func playMyFile(sender: AnyObject) {

    let fileString = NSBundle.mainBundle().pathForResource("audioFile", ofType: "m4a")
    let url = NSURL(fileURLWithPath: fileString)
    var error : NSError?
    audioPlayer = AVAudioPlayer(contentsOfURL: url, error: &error)
    audioPlayer.delegate = self
    audioPlayer.prepareToPlay()
    if (audioPlayer.isEqual(nil)) {
        println("There was an error: (er)")
    } else {
        audioPlayer.play()
        NSLog("working")
    }

I have added import AVFoundation and audioPlayer is a global variable. When I execute the code, it does print "working", so it makes it through without errors but no sound is played. The device is not in silent.

Answer 1

I had to declare a global player variable

var player: AVAudioPlayer!

and set it in viewDidLoad

   override func viewDidLoad() {
        super.viewDidLoad()
        player = AVAudioPlayer()
    }

Then I could play the audio file wherever like this:

    func playAudioFile(){
    do {
        if audioFileUrl == nil{
            return 
        }
           try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
           try AVAudioSession.sharedInstance().setActive(true)
           /* The following line is required for the player to work on iOS 11. Change the file type accordingly*/
           player = try AVAudioPlayer(contentsOf: audioFileUrl, fileTypeHint: AVFileType.m4a.rawValue)
           /* iOS 10 and earlier require the following line:
           player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileTypeMPEGLayer3) */
           guard let player = player else { return }
           player.play()
        print("PLAYING::::: \(audioFileUrl)")
       }
    catch let error {
           print(error.localizedDescription)
       }
}

}

Answer 2

There's so much wrong with your code that Socratic method breaks down; it will probably be easiest just to throw it out and show you:

var player : AVAudioPlayer! = nil // will be Optional, must supply initializer

@IBAction func playMyFile(sender: AnyObject?) {
    let path = NSBundle.mainBundle().pathForResource("audioFile", ofType:"m4a")
    let fileURL = NSURL(fileURLWithPath: path)
    player = AVAudioPlayer(contentsOfURL: fileURL, error: nil)
    player.prepareToPlay()
    player.delegate = self
    player.play()
}

I have not bothered to do any error checking, but the upside is you'll crash if there's a problem.

One final point, which may or may not be relevant: not every m4a file is playable. A highly compressed file, for example, can fail silently (pun intended).

Answer 3

Important that AvPlayer is class member and not in the given function, else it goes out of scope... :)

Answer 4

Here is a working snippet from my swift project. Replace "audiofile" by your file name.

    var audioPlayer = AVAudioPlayer()
    let audioPath = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("audiofile", ofType: "mp3"))
    audioPlayer = AVAudioPlayer(contentsOfURL: audioPath, error: nil)
    audioPlayer.delegate = self
    audioPlayer.prepareToPlay()
    audioPlayer.play()

You can download fully functional Swift Audio Player application source code from here https://github.com/bpolat/Music-Player