OutputSignWave.swift

import UIKit
import AVFoundation

let player = AVAudioPlayerNode()
let engine = AVAudioEngine()
engine.attach(player)
engine.connect(player, to: engine.mainMixerNode, format: player.outputFormat(forBus: 0))

try! engine.start()
player.play()
let format =  player.outputFormat(forBus: 0)
let sampleRate = format.sampleRate
var buf = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: AVAudioFrameCount(sampleRate))!
buf.frameLength = AVAudioFrameCount(sampleRate)

for ch in 0..<format.channelCount {
    let samples = buf.floatChannelData![Int(ch)]
    for n in 0..<buf.frameLength {
        samples[Int(n)] = sinf(Float(2.0 * Double.pi) * 440.0 * Float(n) / Float(sampleRate))
    }
}

player.scheduleBuffer(buf) {
    print("complete")
}