renarl · November 14, 2022 17:33 · May 23, 2021 · May 23, 2021
diff --git a/pure_tone.swift b/pure_tone.swift
@@ -26,7 +26,7 @@ Copyright (c) 2021 Lee Barney
 import Foundation
 import AVFoundation
 
-func playPureTone(frequencyInHz: Int, amplitude: Float, durationInMillis: Int, completionBlock: @escaping ()->Void) {
+func playPureTone(frequencyInHz: Int, amplitude: Float, durationInMillis: Int, completion: @escaping ()->Void) {
     //Use a semaphore to block until the tone completes playing
     let semaphore = DispatchSemaphore(value: 1)
     //Run async in the background so as not to block the current thread

diff --git a/pure_tone.swift b/pure_tone.swift
@@ -0,0 +1,84 @@
+//
+//
+//  Swift Pure Tone Generation
+//
+/*
+Copyright (c) 2021 Lee Barney
+ Permission is hereby granted, free of charge, to any person obtaining a
+ copy of this software and associated documentation files (the "Software"),
+ to deal in the Software without restriction, including without limitation the
+ rights to use, copy, modify, merge, publish, distribute, sublicense,
+ and/or sell copies of the Software, and to permit persons to whom the Software
+ is furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice shall be
+ included in all copies or substantial portions of the Software.
+
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+ PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+ CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
+ OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+import Foundation
+import AVFoundation
+
+func playPureTone(frequencyInHz: Int, amplitude: Float, durationInMillis: Int, completionBlock: @escaping ()->Void) {
+    //Use a semaphore to block until the tone completes playing
+    let semaphore = DispatchSemaphore(value: 1)
+    //Run async in the background so as not to block the current thread
+    DispatchQueue.global().async {
+        //Build the player and its engine
+        let audioPlayer = AVAudioPlayerNode()
+        let audioEngine = AVAudioEngine()
+        semaphore.wait()//Claim the semphore for blocking
+        audioEngine.attach(audioPlayer)
+        let mixer = audioEngine.mainMixerNode
+        let sampleRateHz = Float(mixer.outputFormat(forBus: 0).sampleRate)
+
+        guard let format = AVAudioFormat(commonFormat: AVAudioCommonFormat.pcmFormatFloat32, sampleRate: Double(sampleRateHz), channels: AVAudioChannelCount(1), interleaved: false) else {
+            return
+        }
+        // Connect the audio engine to the audio player
+        audioEngine.connect(audioPlayer, to: mixer, format: format)
+
+
+        let numberOfSamples = AVAudioFrameCount((Float(durationInMillis) / 1000 * sampleRateHz))
+        //create the appropriatly sized buffer
+        guard let buffer  = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: numberOfSamples) else {
+            return
+        }
+        buffer.frameLength = numberOfSamples
+        //get a pointer to the buffer of floats
+        let channels = UnsafeBufferPointer(start: buffer.floatChannelData, count: Int(format.channelCount))
+        let floats = UnsafeMutableBufferPointer<Float>(start: channels[0], count: Int(numberOfSamples))
+        //calculate the angular frequency
+        let angularFrequency = Float(frequencyInHz * 2) * .pi
+        // Generate and store the sequential samples representing the sine wave of the tone
+        for i in 0 ..< Int(numberOfSamples) {
+            let waveComponent = sinf(Float(i) * angularFrequency / sampleRateHz)
+            floats[i] = waveComponent * amplitude
+        }
+        do {
+            try audioEngine.start()
+        }
+        catch{
+            print("Error: Engine start failure")
+            return
+        }
+
+        // Play the pure tone represented by the buffer
+        audioPlayer.play()
+        audioPlayer.scheduleBuffer(buffer, at: nil, options: .interrupts){
+            DispatchQueue.main.async {
+                completionBlock()
+                semaphore.signal()//Release one claim of the semiphore
+            }
+        }
+        semaphore.wait()//Wait for the semiphore so the function doesn't end before the playing of the tone completes
+        semaphore.signal()//Release the other claim of the semiphore
+    }
+}