CODEWITHSUNDEEP
iosxcodeswift
CoolPenguin
CoolPenguin

Reputation: 1235

AVAudioEngine() Playback Not Working

I'm trying to change the pitch of a sound using the AVAudioEngine() in Swift. This is my code:

func setUpEngine() {
    let fileString = NSBundle.mainBundle().pathForResource("400", ofType: "wav")
    let url = NSURL(fileURLWithPath: fileString!)
    do {
        try audioFile = AVAudioFile(forReading: url)
        print("done")
    }
    catch{

    }
}
var engine = AVAudioEngine()
var audioFile = AVAudioFile()
var audioPlayerNode = AVAudioPlayerNode()
var changeAudioUnitTime = AVAudioUnitTimePitch()
override func viewDidLoad() {
    setUpEngine()
    let defaults = NSUserDefaults.standardUserDefaults()
    audioPlayerNode.stop()
    engine.stop()
    engine.reset()
    engine.attachNode(audioPlayerNode)
    changeAudioUnitTime.pitch = 800
    engine.attachNode(changeAudioUnitTime)
    engine.connect(audioPlayerNode, to: changeAudioUnitTime, format: nil)
    engine.connect(changeAudioUnitTime, to: engine.outputNode, format: nil)
    audioPlayerNode.scheduleFile(audioFile, atTime: nil, completionHandler: nil)
    engine.startAndReturnError(nil)
    audioPlayerNode.play()

The rest of my code is below (I do close the brackets). I found most of this code online and I get an error with the line 

engine.startAndReturnError(nil)

'Value of type has no member'.

When I remove this line I get the following error:

'AVAudioPlayerNode.mm:333: Start: required condition is false: _engine->IsRunning() Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'required condition is false: _engine->IsRunning()''

Any help would be greatly appreciated. I am using Swift in xCode and a single view application.

Upvotes: 3

Views: 4919

Answers (2)

Pescolly
Pescolly

Reputation: 942

The error is that the engine is not running. You need to reorder your operations like this...

setUpEngine()
let defaults = NSUserDefaults.standardUserDefaults()
engine.attachNode(audioPlayerNode)
engine.attachNode(changeAudioUnitTime)
engine.connect(audioPlayerNode, to: changeAudioUnitTime, format: nil)
engine.connect(changeAudioUnitTime, to: engine.outputNode, format: nil)
changeAudioUnitTime.pitch = 800
engine.prepare()    
engine.start()    
audioPlayerNode.scheduleFile(audioFile, atTime: nil, completionHandler: nil)
audioPlayerNode.play()

Some time later...

engine.stop()

Upvotes: 4

Jeeva
Jeeva

Reputation: 162

This is because you are running on either outdated version of XCode or incompatible version of iOS. I had this issue and in the latest Swift version there is no such method instead they provide .start().

Upvotes: 0

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