Photokit

PhotoKit

Build media selection, camera capture, photo library queries, and image caching workflows with PhotosUI (PhotosPicker), PhotoKit (PHPhotoLibrary), and AVFoundation. Targets Swift 6.3 / iOS 26+.

Contents

• Picker Selection Strategy
• Privacy and Permissions
• Image Loading and Caching
• Camera Capture Boundaries
• Route by Task
• Common Mistakes
• Review Checklist
• References

Picker Selection Strategy

Prefer PhotosPicker for standard media selection. It preserves user privacy and eliminates permission friction.

Privacy and Permissions

When accessing PHPhotoLibrary directly, request authorization and handle .limited access:

let status = await PHPhotoLibrary.requestAuthorization(for: .readWrite)
switch status {
case .authorized:
    // Full photo library access granted
case .limited:
    // User selected specific photos (present PHPhotoLibrary.shared().presentLimitedLibraryPicker)
case .denied, .restricted:
    // Direct user to Settings
case .notDetermined:
    break
@unknown default:
    break
}

Include NSPhotoLibraryUsageDescription (read/write) or NSPhotoLibraryAddUsageDescription (write-only save) in Info.plist.

Image Loading and Caching

Use PHCachingImageManager for fast grid thumbnail generation:

1. Prepare caching: Call startCachingImages(for:targetSize:contentMode:options:) when scrolling into view.
2. Reuse options: Use PHImageRequestOptions with deliveryMode = .opportunistic for quick thumbnails followed by high-res data.
3. Cancel obsolete requests: Cancel pending request IDs when cells scroll out of viewport.

Camera Capture Boundaries

For custom camera viewfinders using AVCaptureSession:

• Configure sessions on a dedicated serial background queue, never on @MainActor.
• Balance every transaction with session.beginConfiguration() and defer { session.commitConfiguration() }.
• Embed viewfinders in SwiftUI using UIViewRepresentable backed by AVCaptureVideoPreviewLayer.

Route by Task

• For SwiftUI PhotosPicker single/multi-selection and media filtering recipes, read PhotosPicker Recipes.
• For complete camera controllers, photo capture, video recording, and barcode scanning, read Camera Capture Patterns.
• For asset fetching, thumbnail caching with PHCachingImageManager, and memory management, read Image Loading and Caching. For format conversion and compression, read Image Formats and Compression.
• For video playback, custom player UI, and AVPlayer integration, read AV Playback Reference.

Common Mistakes

• Requesting full photo library permissions when PhotosPicker would suffice without any permissions.
• Hardcoding .highQualityFormat on PHImageRequestOptions for fast-scrolling grids, causing dropped frames.
• Running AVCaptureSession.startRunning() or configuration changes on @MainActor.
• Forgetting to handle .limited photo library access on iOS 14+.
• Loading full-resolution UIImage into memory for multiple items simultaneously without downsampling.

Review Checklist

• PhotosPicker preferred over custom library enumeration where appropriate
• NSPhotoLibraryUsageDescription provided when using PHPhotoLibrary
• NSCameraUsageDescription provided when using AVCaptureSession
• .limited photo library authorization handled gracefully
• PHCachingImageManager used with preheating for asset collections
• AVCaptureSession configured and started on a serial background queue
• Photo picker item loading handles cancellation and errors asynchronously
• Image assets downsampled to target display size to prevent memory spikes

References

• PhotoKit patterns and picker recipes
• Camera capture and AVCaptureSession reference
• Image loading, caching, and downsampling
• Image formats and compression
• AV Playback reference
• PhotoKit documentation
• PhotosUI documentation