Camera Capture

AVFoundation camera patterns for custom camera UIs. Covers session setup, photo capture, video recording, rotation handling, responsive capture pipeline, and session lifecycle management.

When to Use

Use this skill when you're:

• Building a custom camera UI (not the system picker)
• Capturing photos with quality/speed tradeoffs
• Recording video with audio
• Handling device rotation correctly with RotationCoordinator (iOS 17+)
• Making capture feel instant (zero-shutter-lag, deferred processing)
• Making camera launch fast with deferred start (iOS 26 and later)
• Recording high-data-rate video (ProRes) with Pro Video Storage (iOS 27)
• Handling session interruptions (phone calls, multitasking, thermal pressure)
• Switching between front and back cameras
• Switching cameras on iPhone Duo's two front cameras (the virtual front camera, available today; a camera-direction API from iOS 27.1)

Note: If you just need users to pick existing photos, use photo-library instead. This skill is for building custom camera experiences with AVCaptureSession.

Example Prompts

Questions you can ask Claude that will draw from this skill:

• "How do I set up a camera preview in SwiftUI?"
• "My camera freezes when I get a phone call"
• "The photo preview is rotated wrong on front camera"
• "How do I make photo capture feel instant?"
• "Should I use deferred processing?"
• "How do I switch between front and back cameras?"
• "How do I record video with audio?"
• "My camera takes too long to capture"
• "My camera app launches slowly — the preview takes forever to appear"
• "My ProRes recording drops frames"
• "How do I support the two front cameras on iPhone Duo?"

What This Skill Provides

Session Architecture

• AVCaptureSession setup with dedicated serial queue
• Input/output configuration with atomic beginConfiguration/commitConfiguration
• Session presets for photo vs video use cases

Capture Patterns

• Basic photo capture with AVCapturePhotoOutput
• Video recording with AVCaptureMovieFileOutput and audio
• Camera switching between front and back with fallback handling

Responsive Capture Pipeline (iOS 17+)

• Zero-shutter-lag with ring buffer for instant capture
• Responsive capture for overlapping photo captures
• Fast capture prioritization for burst-like shooting
• Readiness coordinator for shutter button state management
• Deferred processing with proxy images and background processing

Launch Performance and Pro Recording

• Deferred start for fast launch — preview up in roughly half the time (iOS 26 and later)
• Automatic vs manual deferred start, including the video-data-output preview case
• Pro Video Storage for deterministic ProRes file writes (iOS 27)

Rotation and Orientation

• RotationCoordinator for automatic rotation tracking (replaces deprecated videoOrientation)
• KVO observation for preview angle updates
• Capture angle application for correctly oriented photos

Session Lifecycle

• Interruption handling (phone calls, Split View, thermal pressure)
• Proper start/stop on background queue
• UI feedback patterns for interrupted states

Pressure Scenarios

• Shipping camera features under deadline pressure
• Responding to "camera is too slow" complaints
• Explaining front camera mirroring behavior to designers

Key Pattern

SwiftUI Camera Preview

struct CameraPreview: UIViewRepresentable {
    let session: AVCaptureSession

    func makeUIView(context: Context) -> PreviewView {
        let view = PreviewView()
        view.previewLayer.session = session
        view.previewLayer.videoGravity = .resizeAspectFill
        return view
    }

    func updateUIView(_ uiView: PreviewView, context: Context) {}

    class PreviewView: UIView {
        override class var layerClass: AnyClass { AVCaptureVideoPreviewLayer.self }
        var previewLayer: AVCaptureVideoPreviewLayer { layer as! AVCaptureVideoPreviewLayer }
    }
}

Documentation Scope

This page documents the axiom-media skill -- AVFoundation camera patterns Claude uses when helping you build custom camera features. The skill contains 9 core patterns with code examples, anti-patterns, a shipping checklist, and pressure scenarios.

For diagnostics: See camera-capture-diag for troubleshooting black previews, frozen cameras, and rotation issues.

For API reference: See camera-capture-ref for comprehensive AVCaptureSession, AVCapturePhotoOutput, and RotationCoordinator API coverage.

Related

• camera-capture-diag – Troubleshooting camera issues (black preview, rotation, slow capture)
• camera-capture-ref – Complete AVFoundation camera API reference
• photo-library – Photo picking and library access (use instead if you just need photo selection)
• iPhone Duo – front-camera switching, direction vs. position, and showing camera UI on both displays

Resources

WWDC: 2021-10247, 2023-10105, 2026-303

Tech Talks: 111465

Docs: /avfoundation/avcapturesession, /avfoundation/avcapturedevice/rotationcoordinator, /avfoundation/avprovideostorage