在SwiftUI中观察系统卷

import AVFoundation
import SwiftUI

class VolumeObserver: ObservableObject {
    @Published var volume: Float = 0.0
    
    init() {
        let audioSession = AVAudioSession.sharedInstance()
        do {
            try audioSession.setActive(true)
            audioSession.addObserver(self, forKeyPath: "outputVolume", options: [.new], context: nil)
        } catch {
            print("Failed to observe system volume")
        }
    }
    
    deinit {
        let audioSession = AVAudioSession.sharedInstance()
        audioSession.removeObserver(self, forKeyPath: "outputVolume")
    }
    
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        guard keyPath == "outputVolume" else { return }
        guard let newVolume = change?[.newKey] as? Float else { return }
        DispatchQueue.main.async {
            self.volume = newVolume
        }
    }
}

struct ContentView: View {
    @ObservedObject var volumeObserver = VolumeObserver()
    
    var body: some View {
        VStack {
            Text("当前系统音量：\(volumeObserver.volume)")
        }
        .onReceive(volumeObserver.$volume) { volume in
            // 在这里执行相应的操作，例如调整应用程序的音量
        }
    }
}