Pitch Shifting in Real Time With AVAudioEngine using Swift

timePitch.pitch = -500 //Rude man voicetimePitch.rate = 1.5 //In 1.5 times faster

Check this tutorial. And direct link to example from tutorial for more info.

Example for Swift 2.0:

import UIKitimport AVFoundationclass ViewController: UIViewController {    var engine: AVAudioEngine!    var player: AVAudioPlayerNode!    var file = AVAudioFile()    override func viewDidLoad() {        super.viewDidLoad()        engine = AVAudioEngine()        player = AVAudioPlayerNode()        player.volume = 1.0        let path = NSBundle.mainBundle().pathForResource("in", ofType: "caf")!        let url = NSURL.fileURLWithPath(path)        let file = try? AVAudioFile(forReading: url)        let buffer = AVAudioPCMBuffer(PCMFormat: file!.processingFormat, frameCapacity: AVAudioFrameCount(file!.length))        do {            try file!.readIntoBuffer(buffer)        } catch _ {        }        let pitch = AVAudioUnitTimePitch()        //        pitch.pitch = -500 //Distortion        pitch.rate = 1.5 //Voice speed        //        engine.attachNode(player)        engine.attachNode(pitch)        engine.connect(player, to: pitch, format: buffer.format)        engine.connect(pitch, to: engine.mainMixerNode, format: buffer.format)        player.scheduleBuffer(buffer, atTime: nil, options: AVAudioPlayerNodeBufferOptions.Loops, completionHandler: nil)        engine.prepare()        do {            try engine.start()        } catch _ {        }        player.play()    }}

timePitch.pitch = 1000 //Filtered VoicetimePitch.rate = 1 //Normal rate