AVFoundation is Apple's high-level framework for working with time-based audiovisual media. For audio, it supports:

• Playback with AVAudioPlayer
• Recording with AVAudioRecorder
• Advanced audio processing with AVAudioEngine
• Real-time capture and manipulation via AVCaptureAudioDataOutput

AVAudioPlayer is used to play audio files locally from the app bundle or filesystem.

let url = URL(fileURLWithPath: "/path/to/audio.mp3")
let player = try AVAudioPlayer(contentsOf: url)
player.prepareToPlay()
player.play()
    

🔍 Common methods:

• play() – Starts playback
• pause() – Pauses playback
• stop() – Stops playback and resets position

🎛️ Useful properties:

• volume – Adjust playback volume (0.0 to 1.0)
• numberOfLoops – Set to -1 to loop indefinitely
• duration – Total duration of the audio

AVAudioRecorder allows you to capture microphone input and save it to a file.

let settings = [
    AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
    AVSampleRateKey: 12000,
    AVNumberOfChannelsKey: 1,
    AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
]
let recorder = try AVAudioRecorder(url: fileURL, settings: settings)
recorder.record()
    

📌 Tips:

• Always call AVAudioSession.sharedInstance().setCategory(_:mode:options:) before recording
• Request mic access using AVCaptureDevice.requestAccess(for: .audio)
• Check for file format compatibility with iOS (e.g., AAC, M4A)

AVAudioEngine provides a powerful modular system for manipulating audio streams in real time.

let engine = AVAudioEngine()
let playerNode = AVAudioPlayerNode()
engine.attach(playerNode)

let mixer = engine.mainMixerNode
engine.connect(playerNode, to: mixer, format: nil)

try engine.start()
playerNode.play()
    

⚙️ Core Components:

• AVAudioPlayerNode – Play audio buffers or files
• AVAudioUnitEffect – Add effects like reverb
• AVAudioMixerNode – Mix multiple sources

🧠 Note: AVAudioEngine is ideal for low-latency audio, real-time FX, and interactive sound design.

This is part of AVCaptureSession and allows you to get live microphone data in real-time buffers.

let audioOutput = AVCaptureAudioDataOutput()
audioOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "audioQueue"))
captureSession.addOutput(audioOutput)
    

🧪 You can use this to pipe audio into an AVAudioEngine or encode it manually using AudioToolbox.

Before playing or recording, configure your AVAudioSession to inform the system how your app uses audio.

let session = AVAudioSession.sharedInstance()
try session.setCategory(.playAndRecord, mode: .default)
try session.setActive(true)
    

📌 Categories:

• .playback – For playing audio only
• .record – For recording only
• .playAndRecord – For both simultaneously

⚠️ Always activate the session before starting playback or recording!

Here are common issues and how to fix them:

• Error Code -10868 – Incompatible audio format or session misconfiguration. Ensure formats match input/output.
• nil AVAudioPlayer – Ensure the file exists and is not protected or corrupted.
• ❗Use try/catch for all AVFoundation object initializations to handle silent failures.