AVKit Audio and Haptic Feedback¶

AVKit provides audio playback for background music and sound effects. UIKit's feedback generators provide haptic feedback on physical devices. This entry covers the two-player audio pattern and haptic integration in SwiftUI.

Key Facts¶

AVAudioPlayer plays audio files from the app bundle
Use two separate players (music + SFX) - one player causes SFX to interrupt music permanently
numberOfLoops = -1 loops audio indefinitely
Haptic feedback uses UINotificationFeedbackGenerator from UIKit
Haptics only work on physical devices, not the simulator
Audio files must be added to the app bundle (drag into Xcode project)

Patterns¶

Two-Player Audio Pattern¶

import AVKit

struct GameplayView: View {
    @State private var musicPlayer: AVAudioPlayer!
    @State private var sfxPlayer: AVAudioPlayer!

    private func playMusic() {
        let songs = [
            "let the mystery unfold",
            "spellcraft",
            "hiding place in the forest",
            "deep in the dell"
        ]
        let i = Int.random(in: 0...3)

        if let sound = Bundle.main.path(forResource: songs[i], ofType: "mp3") {
            musicPlayer = try! AVAudioPlayer(
                contentsOf: URL(fileURLWithPath: sound)
            )
            musicPlayer.numberOfLoops = -1   // loop forever
            musicPlayer.volume = 0.1         // 10% - subtle background
            musicPlayer.play()
        }
    }

    private func playSFX(_ name: String) {
        if let sound = Bundle.main.path(forResource: name, ofType: "mp3") {
            sfxPlayer = try! AVAudioPlayer(
                contentsOf: URL(fileURLWithPath: sound)
            )
            sfxPlayer.play()
        }
    }

    var body: some View {
        // ...
        .onAppear { playMusic() }
    }
}

Key: numberOfLoops = -1 loops indefinitely. volume = 0.1 keeps background music subtle.

Sound Effects¶

private func playFlipSound() {
    playSFX("page flip")
}

private func playWrongSound() {
    playSFX("negative beeps")
}

private func playCorrectSound() {
    playSFX("magic wand")
}

Haptic Feedback¶

import UIKit

private func giveWrongFeedback() {
    let generator = UINotificationFeedbackGenerator()
    generator.notificationOccurred(.error)
}

// Call outside withAnimation - haptic is not animated
.onTapGesture {
    withAnimation { /* visual changes */ }
    giveWrongFeedback()   // haptic separate from animation
}

Haptic types: - .error - three quick taps (wrong answer) - .success - two taps (correct answer) - .warning - single strong tap

Audio Volume Levels¶

Context	Volume	Reason
Background music	0.1	Subtle, non-distracting
Sound effects	1.0 (default)	Clear feedback
UI sounds	0.3-0.5	Noticeable but not loud

Gotchas¶

Using a single AVAudioPlayer for both music and SFX causes music to stop permanently when an SFX plays
try! on AVAudioPlayer init is acceptable for bundled files; network audio should use try/catch
Bundle.main.path(forResource:ofType:) returns nil if the file is not in the bundle - verify file names
Haptics do nothing in the simulator - test on a real device
AVAudioPlayer must be stored as a property (@State) or it gets deallocated and stops playing
Audio playback may conflict with other apps - consider AVAudioSession configuration for production apps