Audio Player written for SwiftUI - first pass

AudioPlayerView.swift

//
//  AudioPlayerView.swift
//  AccessibleAudioPlayer
//
//  Created by Laurent B on 30/10/2021.
//

import SwiftUI
import AVKit

struct AudioPlayerView: View {
	@State var audioPlayer: AVAudioPlayer!
	@State var progress: CGFloat = 0.0
	@State private var playing: Bool = false
	@State var duration: Double = 0.0
	@State var formattedDuration: String = ""
	@State var formattedProgress: String = "00:00"

	var body: some View {
		VStack {
			Text("Audio Player")
				.bold()
				.multilineTextAlignment(.center)
				.font(.title)
				.minimumScaleFactor(0.75)
				.padding()

			HStack {
				Text(formattedProgress)
					.font(.caption.monospacedDigit())

				// this is a dynamic length progress bar
				GeometryReader { gr in
					Capsule()
						.stroke(Color.blue, lineWidth: 2)
						.background(
							Capsule()
								.foregroundColor(Color.blue)
								.frame(width: gr.size.width * progress, height: 8), alignment: .leading)
				}
				.frame( height: 8)

				Text(formattedDuration)
					.font(.caption.monospacedDigit())
			}
			.padding()
			.frame(height: 50, alignment: .center)
			.accessibilityElement(children: .ignore)
			.accessibility(identifier: "audio player")
			.accessibilityLabel(playing ? Text("Playing at ") : Text("Duration"))
			.accessibilityValue(Text("\(formattedProgress)"))

			//			 the control buttons
			HStack(alignment: .center, spacing: 20) {
				Spacer()
				Button(action: {
					let decrease = self.audioPlayer.currentTime - 15
					if decrease < 0.0 {
						self.audioPlayer.currentTime = 0.0
					} else {
						self.audioPlayer.currentTime -= 15
					}
				}) {
					Image(systemName: "gobackward.15")
						.font(.title)
						.imageScale(.medium)
				}

				Button(action: {
					if audioPlayer.isPlaying {
						playing = false
						self.audioPlayer.pause()
					} else if !audioPlayer.isPlaying {
						playing = true
						self.audioPlayer.play()
					}
				}) {
					Image(systemName: playing ?
						  "pause.circle.fill" : "play.circle.fill")
						.font(.title)
						.imageScale(.large)
				}

				Button(action: {
					let increase = self.audioPlayer.currentTime + 15
					if increase < self.audioPlayer.duration {
						self.audioPlayer.currentTime = increase
					} else {
						// give the user the chance to hear the end if he wishes
						self.audioPlayer.currentTime = duration
					}
				}) {
					Image(systemName: "goforward.15")
						.font(.title)
						.imageScale(.medium)
				}
				Spacer()
			}
		}
		.foregroundColor(.blue)
		.onAppear {
			initialiseAudioPlayer()
		}
	}

	func initialiseAudioPlayer() {
		let formatter = DateComponentsFormatter()
		formatter.allowedUnits = [.minute, .second]
		formatter.unitsStyle = .positional
		formatter.zeroFormattingBehavior = [ .pad ]

		// init audioPlayer
		let path = Bundle.main.path(forResource: "audioTest", ofType: "m4a")!
		self.audioPlayer = try! AVAudioPlayer(contentsOf: URL(fileURLWithPath: path))
		self.audioPlayer.prepareToPlay()

		//I need both! The formattedDuration is the string to display and duration is used when forwarding
		formattedDuration = formatter.string(from: TimeInterval(self.audioPlayer.duration))!
		duration = self.audioPlayer.duration

		Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { _ in
			if !audioPlayer.isPlaying {
				playing = false
			}
			progress = CGFloat(audioPlayer.currentTime / audioPlayer.duration)
			formattedProgress = formatter.string(from: TimeInterval(self.audioPlayer.currentTime))!
		}
	}
}

struct AudioPlayerView_Previews: PreviewProvider {
	static var previews: some View {
		AudioPlayerView()
			.previewLayout(PreviewLayout.fixed(width: 500, height: 300))
			.previewDisplayName("Default preview")
		AudioPlayerView()
			.previewLayout(PreviewLayout.fixed(width: 500, height: 300))
			.environment(\.sizeCategory, .accessibilityExtraLarge)
	}
}