How to determine if AVPlayer stopped

Hi, I have the following code. How can I reset the button to "play" when the file stopped playing? Thank you for your help.

import SwiftUI
import AVFoundation
struct ContentView: View {
  @StateObject private var soundManager = SoundManager()
  @State var song1 = false
  @State var buttonImage: Image = (Image(systemName: "play.circle.fill"))
  var body: some View {
    VStack {
      Button(action: {
        soundManager.playSound("https://freetestdata.com/wp-content/uploads/2021/09/Free_Test_Data_100KB_MP3.mp3")
        song1.toggle()
        if song1 {
          soundManager.audioPlayer?.play()
          updateButtonImage(image: "pause.circle.fill")
        } else {
          soundManager.audioPlayer?.pause()
          updateButtonImage(image: "play.circle.fill")
        }
      }) {
        buttonImage
          .resizable()
          .frame(width: 50, height: 50)
      }
    }
  }
  private func updateButtonImage(image: String) {
    buttonImage = Image(systemName: image)
  }
}
class SoundManager : ObservableObject {
  var audioPlayer: AVPlayer?
  func playSound(_ sound: String){
    if let url = URL(string: sound) {
      self.audioPlayer = AVPlayer(url: url)
    }
  }
}
struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
    ContentView()
  }
}