While recording the sound in my application, I measure its decibel and display it on the screen in the UI. However, in the UI, I want to divide the sound entering from the current microphone into frequencies and show it in a graph. I tried to add AVAudioInputNode to this class (https://github.com/vNakamura/SwiftChartsAudioVisualizer/blob/main/SwiftChartsAudioVisualizer/AudioProcessing.swift) to process only the sound, regardless of Decibel measurement, but it still did not work. I need your help.

Thanks!

import Foundation
import AVFoundation
import UIKit
import CoreAudio

class DecibelRecorder: NSObject, ObservableObject, AVAudioRecorderDelegate {
    @Published var decibel = 0
    @Published var avgDecibel = 0
    @Published var peakDecibel = 0

    let kRecordAudioFile = "myRecord.caf"
    var audioRecorder: AVAudioRecorder?
    var audioPlayer: AVAudioPlayer?
    var timer: Timer?
    var isRecording = false
    static var url: URL?
    
    func setAudioSession() {
        let audioSession = AVAudioSession.sharedInstance()
        
        do {
            // Set to play and record state, so that the recording can be played after recording
            try audioSession.setCategory(.playAndRecord)
            try audioSession.setActive(true)
        } catch {
            print("Failed to set audio session: (error.localizedDescription)")
        }
    }
    
    
    func getSavePath() -> URL? {
        guard let urlStr = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).last else {
            return nil
        }
        
        let url = URL(fileURLWithPath: urlStr).appendingPathComponent(kRecordAudioFile)
        print("file path: (url.path)")
        
        DecibelRecorder.url = url
        return url
    }
    
    func getAudioSetting() -> [String: Any] {
        var settings: [String: Any] = [:]
        
        settings[AVFormatIDKey] = kAudioFormatLinearPCM
        settings[AVSampleRateKey] = 8000
        settings[AVNumberOfChannelsKey] = 2
        settings[AVLinearPCMBitDepthKey] = 8
        settings[AVLinearPCMIsFloatKey] = true
        settings[AVSampleRateConverterAudioQualityKey] = AVAudioQuality.high.rawValue
        
        return settings
    }
    
    
    var audioRecorderr: AVAudioRecorder? {
        if audioRecorder == nil {
                // route
            guard let url = getSavePath() else {
                return nil
            }
                // recording settings
            let settings = getAudioSetting()
            
                // create recorder
            do {
                audioRecorder = try AVAudioRecorder(url: url, settings: settings)
                audioRecorder?.delegate = self
                audioRecorder?.isMeteringEnabled = true
            } catch {
                print("Failed to create audio recorder: (error.localizedDescription)")
                return nil
            }
        }
        
        return audioRecorder
    }
    
    
    var timerr: Timer? {
        if timer == nil {
            timer = Timer.scheduledTimer(timeInterval: 0.7, target: self, selector: #selector(audioPowerChange), userInfo: nil, repeats: true)
        }
        return timer
    }
    
    
    @objc func audioPowerChange() {
        self.audioRecorderr?.updateMeters() //update measurements
        let power = self.audioRecorderr?.averagePower(forChannel: 0) ?? 0.0
        let powerMax = self.audioRecorderr?.peakPower(forChannel: 0) ?? 0.0
        
        let adjustedPower = power + 155 - 50
        
        var dB = 0
        if adjustedPower < 0.0 {
            dB = 0
        } else if adjustedPower < 40.0 {
            dB = Int(adjustedPower * 0.875)
        } else if adjustedPower < 100.0 {
            dB = Int(adjustedPower - 15)
        } else if adjustedPower < 110.0 {
            dB = Int(adjustedPower * 2.5 - 165)
        } else {
            dB = 110
        }
        
        self.avgDecibel = Int(abs(power))
        self.peakDecibel = Int(abs(powerMax))
        
        //showing in UI
        self.decibel = dB
    }
    
    // MARK: - UI Events
    
    func recordClick() {
        if !(audioRecorderr?.isRecording ?? false) {
            isRecording = true
            audioRecorderr?.record()
            timerr?.fireDate = Date.distantPast
        }
    }
    
    func pauseClick() {
        if audioRecorderr?.isRecording ?? false {
            isRecording = false
            audioRecorderr?.pause()
            timerr?.fireDate = Date.distantFuture
        }
    }
    
    
    func stopClick() {
        isRecording = false
        audioRecorderr?.stop()
        timerr?.fireDate = Date.distantFuture
    }
    
    // MARK: - Recorder proxy method
    
    func audioRecorderDidFinishRecording(_ recorder: AVAudioRecorder, successfully flag: Bool) {
        if !(audioPlayer?.isPlaying ?? false) {
            audioPlayer?.play()
        }
        print("Recording complete!")
    }
}