How to resolve "Cannot find 'AKMicrophoneTracker' in scope"?

// This section imports necessary libraries.
import SwiftUI  // Library for building user interfaces on Apple platforms.
import AudioKit  // Library for audio processing.

// This is the main content view of your app.
struct ContentView: View {

    // This section declares properties that store data for the view.

    // 'pitch' holds the detected pitch frequency value.
    @State private var pitch: Double = 0.0

    // 'isRecording' is a flag that checks whether the microphone is currently recording.
    @State private var isRecording = false

    // 'mic' is an instance of the AKMicrophoneTracker class from AudioKit which tracks microphone input.
    private var mic: AKMicrophoneTracker!

    // This is the initializer for the ContentView.
    // It's called when an instance of ContentView is created.
    init() {
        // Here, the microphone tracker is initialized.
        mic = AKMicrophoneTracker()
    }

    // The 'body' property defines the user interface for this view.
    var body: some View {
        VStack {
            // This is a text label that displays the detected pitch.
            Text("Pitch: \(pitch, specifier: "%.2f") Hz")
                .padding()  // Adds padding around the text.

            // This is a button the user can tap to start or stop recording.
            Button(action: {
                // This checks if it's currently recording.
                if self.isRecording {
                    // If so, it stops the microphone tracker.
                    self.mic.stop()
                } else {
                    // Otherwise, it starts the microphone tracker.
                    self.mic.start()
                }
                // The 'isRecording' flag is toggled to its opposite value.
                self.isRecording.toggle()
            }) {
                // This displays the button's label, which changes based on whether it's recording.
                Text(isRecording ? "Stop Recording" : "Start Recording")
            }
        }
        // This section repeatedly fetches the frequency from the microphone tracker every 0.1 seconds.
        // and updates the 'pitch' property with the detected frequency.
        .onReceive(Timer.publish(every: 0.1, on: .main, in: .common).autoconnect()) { _ in
            self.pitch = self.mic.frequency
        }
    }
}

// This section provides a preview of the ContentView for the Xcode canvas.
struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

// This section imports necessary libraries.
import SwiftUI  // Library for building user interfaces on Apple platforms.
import AudioKit  // Library for audio processing.

// This is the main content view of your app.
struct ContentView: View {

    // This section declares properties that store data for the view.

    // 'pitch' holds the detected pitch frequency value.
    @State private var pitch: Double = 0.0

    // 'isRecording' is a flag that checks whether the microphone is currently recording.
    @State private var isRecording = false

    // 'mic' is an instance of the AKMicrophoneTracker class from AudioKit which tracks microphone input.
    private var mic: AKMicrophoneTracker!

    // This is the initializer for the ContentView.
    // It's called when an instance of ContentView is created.
    init() {
        // Here, the microphone tracker is initialized.
        mic = AKMicrophoneTracker()
    }

    // The 'body' property defines the user interface for this view.
    var body: some View {
        VStack {
            // This is a text label that displays the detected pitch.
            Text("Pitch: \(pitch, specifier: "%.2f") Hz")
                .padding()  // Adds padding around the text.

            // This is a button the user can tap to start or stop recording.
            Button(action: {
                // This checks if it's currently recording.
                if self.isRecording {
                    // If so, it stops the microphone tracker.
                    self.mic.stop()
                } else {
                    // Otherwise, it starts the microphone tracker.
                    self.mic.start()
                }
                // The 'isRecording' flag is toggled to its opposite value.
                self.isRecording.toggle()
            }) {
                // This displays the button's label, which changes based on whether it's recording.
                Text(isRecording ? "Stop Recording" : "Start Recording")
            }
        }
        // This section repeatedly fetches the frequency from the microphone tracker every 0.1 seconds.
        // and updates the 'pitch' property with the detected frequency.
        .onReceive(Timer.publish(every: 0.1, on: .main, in: .common).autoconnect()) { _ in
            self.pitch = self.mic.frequency
        }
    }
}

// This section provides a preview of the ContentView for the Xcode canvas.
struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}