The code below is modified from AudioKit's Microphone Analysis example. The UI components are written programmatically without using the storyboard. The code is developed with Xcode 8.3.2 (Swift 3.1) and iOS 10.
1. Use
CocoaPods to include the AudioKit framework by add this line to the Podfile:
pod 'AudioKit'
*************** Updated October 4, 2020 for AudioKit 4 *****************
Type this terminal command:pod install
*************************** Update 2020 End *****************************
2. Enable the microphone by adding
NSMicrophoneUsageDescription and a request string such as "This app needs microphone access." to Info.plist.
Your Info.plist should be like this:
When app is run at the first time, this message should be displayed:
Without this modification, you'll see error like this:
This app has crashed because it attempted to access privacy-sensitive data without a usage description. The app's Info.plist must contain an NSMicrophoneUsageDescription key with a string value explaining to the user how the app uses this data.
3. Modify ViewController.swift as below
import UIKit
import AudioKit
class ViewController: UIViewController {
var labelFrequencyValue : UILabel!
var labelAmplitudeValue : UILabel!
var labelSharpValue : UILabel!
var labelFlatValue : UILabel!
let mic = AKMicrophone()
var tracker : AKFrequencyTracker!
override func viewDidLoad() {
super.viewDidLoad()
let labelSing = UILabel(frame: CGRect(x: 0, y: 28, width: view.frame.width, height: 50))
labelSing.text = "Sing into the Microphone"
labelSing.textAlignment = .center
labelSing.font = UIFont.systemFont(ofSize: 24, weight: UIFontWeightBold) //System Font Bold
labelSing.textColor = UIColor.white
labelSing.backgroundColor = UIColor(red: 2/255, green: 181/255, blue: 31/255, alpha: 1.0)
view.addSubview(labelSing)
let labelFrequency = UILabel(frame: CGRect(x: 16, y: 86, width: 85.5, height: 20.5))
labelFrequency.text = "Frequency:"
view.addSubview(labelFrequency)
labelFrequencyValue = UILabel(frame: CGRect(x: view.frame.width-70, y: 86, width: 50, height: 20.5))
labelFrequencyValue.text = "0"
labelFrequencyValue.textAlignment = .right
view.addSubview(labelFrequencyValue)
let labelAmplitude = UILabel(frame: CGRect(x: 16, y: 114.5, width: 85.5, height: 20.5))
labelAmplitude.text = "Amplitude:"
view.addSubview(labelAmplitude)
labelAmplitudeValue = UILabel(frame: CGRect(x: view.frame.width-70, y: 114.5, width: 50, height: 20.5))
labelAmplitudeValue.text = "0"
labelAmplitudeValue.textAlignment = .right
view.addSubview(labelAmplitudeValue)
let labelSharp = UILabel(frame: CGRect(x: 16, y: 142, width: 111.5, height: 20.5))
labelSharp.text = "Note (Sharps):"
view.addSubview(labelSharp)
labelSharpValue = UILabel(frame: CGRect(x: view.frame.width-70, y: 142, width: 50, height: 20.5))
labelSharpValue.text = "C4"
labelSharpValue.textAlignment = .right
view.addSubview(labelSharpValue)
let labelFlat = UILabel(frame: CGRect(x: 16, y: 170.5, width: 94, height: 20.5))
labelFlat.text = "Note (Flats):"
view.addSubview(labelFlat)
labelFlatValue = UILabel(frame: CGRect(x: view.frame.width-70, y: 170.5, width: 50, height: 20.5))
labelFlatValue.text = "F4"
labelFlatValue.textAlignment = .right
view.addSubview(labelFlatValue)
let labelPlot = UILabel(frame: CGRect(x: 0, y: 199, width: view.frame.width, height: 21.5))
labelPlot.text = "Audio Input Plot"
labelPlot.textAlignment = .center
view.addSubview(labelPlot)
tracker = AKFrequencyTracker.init(mic)
let silence = AKBooster(tracker, gain: 0)
AudioKit.output = silence
AudioKit.start()
setupPlot()
Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(updateUI), userInfo: nil, repeats: true)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func setupPlot() {
let audioInputPlot = EZAudioPlot(frame: CGRect(x: 0, y: view.center.y, width: view.frame.width, height: 200))
let plot = AKNodeOutputPlot(mic, frame: audioInputPlot.bounds)
plot.plotType = .rolling
plot.shouldFill = true
plot.shouldMirror = true
plot.color = UIColor.blue
audioInputPlot.addSubview(plot)
view.addSubview(audioInputPlot)
}
func updateUI() {
let noteFrequencies = [16.35,17.32,18.35,19.45,20.6,21.83,23.12,24.5,25.96,27.5,29.14,30.87]
let noteNamesWithSharps = ["C", "C♯","D","D♯","E","F","F♯","G","G♯","A","A♯","B"]
let noteNamesWithFlats = ["C", "D♭","D","E♭","E","F","G♭","G","A♭","A","B♭","B"]
if tracker.amplitude > 0.1 {
labelFrequencyValue.text = String(format: "%0.1f", tracker.frequency)
var frequency = Float(tracker.frequency)
while (frequency > Float(noteFrequencies[noteFrequencies.count-1])){
frequency = frequency / 2.0
}
while (frequency < Float(noteFrequencies[0])) {
frequency = frequency * 2.0
}
var minDistance : Float = 10000.0
var index = 0
for i in 0..<noteFrequencies.count {
let distance = fabsf(Float(noteFrequencies[i]) - frequency)
if (distance < minDistance) {
index = i
minDistance = distance
}
}
let octave = Int(log2f(Float(tracker.frequency) / frequency))
labelSharpValue.text = "\(noteNamesWithSharps[index])\(octave)"
labelFlatValue.text = "\(noteNamesWithFlats[index])\(octave)"
}
labelAmplitudeValue.text = String(format: "%0.2f", tracker.amplitude)
}
}
4. Result:
Related Information
AudioKit
Beethoven (Pitch Detection)
