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dpearson2699/swift-ios-skills/photokit

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PublishedJuly 22, 2026 at 05:31 PM

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version: "1.0.1" name: photokit description: "Implement, review, or improve photo picking, camera capture, and media handling in iOS apps using PhotoKit and AVFoundation. Use when working with PhotosPicker, PHPickerViewController, camera capture sessions (AVCaptureSession), photo library access, image loading and display, video recording, or media permissions. Also use when selecting photos from the library, taking pictures, recording video, processing images, or handling photo/camera privacy permissions in Swift apps."

PhotoKit

Modern patterns for photo picking, camera capture, image loading, and media permissions targeting iOS 26+ with Swift 6.3. Patterns are backward-compatible to iOS 16 unless noted. See references/photokit-patterns.md for complete picker recipes and references/camera-capture.md for AVCaptureSession patterns.

PhotosPicker (SwiftUI, iOS 16+)
Privacy and Permissions
Camera Capture Basics
Image Loading and Display
Common Mistakes
Review Checklist
References

PhotosPicker (SwiftUI, iOS 16+)

PhotosPicker is the native SwiftUI replacement for UIImagePickerController. It runs out-of-process, requires no photo library permission for browsing, and supports single or multi-selection with media type filtering.

Single Selection

swift

import SwiftUI
import PhotosUI
 
struct SinglePhotoPicker: View {
    @State private var selectedItem: PhotosPickerItem?
    @State private var selectedImage: Image?
 
    var body: some View {
        VStack {
            if let selectedImage {
                selectedImage
                    .resizable()
                    .scaledToFit()
                    .frame(maxHeight: 300)
            }
 
            PhotosPicker("Select Photo", selection: $selectedItem, matching: .images)
        }
        .onChange(of: selectedItem) { _, newItem in
            Task {
                if let data = try? await newItem?.loadTransferable(type: Data.self),
                   let uiImage = UIImage(data: data) {
                    selectedImage = Image(uiImage: uiImage)
                }
            }
        }
    }
}

Multi-Selection

swift

struct MultiPhotoPicker: View {
    @State private var selectedItems: [PhotosPickerItem] = []
    @State private var selectedImages: [Image] = []
 
    var body: some View {
        VStack {
            ScrollView(.horizontal) {
                HStack {
                    ForEach(selectedImages.indices, id: \.self) { index in
                        selectedImages[index]
                            .resizable()
                            .scaledToFill()
                            .frame(width: 100, height: 100)
                            .clipShape(.rect(cornerRadius: 8))
                    }
                }
            }
 
            PhotosPicker(
                "Select Photos",
                selection: $selectedItems,
                maxSelectionCount: 5,
                matching: .images
            )
        }
        .onChange(of: selectedItems) { _, newItems in
            Task {
                selectedImages = []
                for item in newItems {
                    if let data = try? await item.loadTransferable(type: Data.self),
                       let uiImage = UIImage(data: data) {
                        selectedImages.append(Image(uiImage: uiImage))
                    }
                }
            }
        }
    }
}

Media Type Filtering

Filter with PHPickerFilter composites to restrict selectable media:

swift

// Images only
PhotosPicker(selection: $items, matching: .images)
 
// Videos only
PhotosPicker(selection: $items, matching: .videos)
 
// Live Photos only
PhotosPicker(selection: $items, matching: .livePhotos)
 
// Screenshots only
PhotosPicker(selection: $items, matching: .screenshots)
 
// Images and videos combined
PhotosPicker(selection: $items, matching: .any(of: [.images, .videos]))
 
// Images excluding screenshots
PhotosPicker(selection: $items, matching: .all(of: [.images, .not(.screenshots)]))

Loading Selected Items with Transferable

PhotosPickerItem loads content asynchronously via loadTransferable(type:). Define a Transferable type for automatic decoding:

swift

struct PickedImage: Transferable {
    let data: Data
    let image: Image
 
    static var transferRepresentation: some TransferRepresentation {
        DataRepresentation(importedContentType: .image) { data in
            guard let uiImage = UIImage(data: data) else {
                throw TransferError.importFailed
            }
            return PickedImage(data: data, image: Image(uiImage: uiImage))
        }
    }
}
 
enum TransferError: Error {
    case importFailed
}
 
// Usage
if let picked = try? await item.loadTransferable(type: PickedImage.self) {
    selectedImage = picked.image
}

Always load in a Task to avoid blocking the main thread. Handle nil returns and thrown errors -- the user may select a format that cannot be decoded.

Privacy and Permissions

Photo Library Access Levels

iOS provides two access levels for the photo library. The system automatically presents the limited-library picker when an app requests .readWrite access -- users choose which photos to share.

Access Level	Description	Info.plist Key
Add-only	Write photos to the library without reading	`NSPhotoLibraryAddUsageDescription`
Read-write	Full or limited read access plus write	`NSPhotoLibraryUsageDescription`

PhotosPicker requires no permission to browse -- it runs out-of-process and only grants access to selected items. Request explicit permission only when you need to read the full library (e.g., a custom gallery) or save photos.

Checking and Requesting Photo Library Permission

swift

import Photos
 
func requestPhotoLibraryAccess() async -> PHAuthorizationStatus {
    let status = PHPhotoLibrary.authorizationStatus(for: .readWrite)
 
    switch status {
    case .notDetermined:
        return await PHPhotoLibrary.requestAuthorization(for: .readWrite)
    case .authorized, .limited:
        return status
    case .denied, .restricted:
        return status
    @unknown default:
        return status
    }
}

Camera Permission

Add NSCameraUsageDescription to Info.plist. Check and request access before configuring a capture session:

swift

import AVFoundation
 
func requestCameraAccess() async -> Bool {
    let status = AVCaptureDevice.authorizationStatus(for: .video)
 
    switch status {
    case .notDetermined:
        return await AVCaptureDevice.requestAccess(for: .video)
    case .authorized:
        return true
    case .denied, .restricted:
        return false
    @unknown default:
        return false
    }
}

Handling Denied Permissions

When the user denies access, guide them to Settings. Never repeatedly prompt or hide functionality silently.

swift

struct PermissionDeniedView: View {
    let message: String
    @Environment(\.openURL) private var openURL
 
    var body: some View {
        ContentUnavailableView {
            Label("Access Denied", systemImage: "lock.shield")
        } description: {
            Text(message)
        } actions: {
            Button("Open Settings") {
                if let url = URL(string: UIApplication.openSettingsURLString) {
                    openURL(url)
                }
            }
        }
    }
}

Required Info.plist Keys

Key	When Required
`NSPhotoLibraryUsageDescription`	Reading photos from the library
`NSPhotoLibraryAddUsageDescription`	Saving photos/videos to the library
`NSCameraUsageDescription`	Accessing the camera
`NSMicrophoneUsageDescription`	Recording audio (video with sound)

Omitting a required key causes a runtime crash when the permission dialog would appear.

Camera Capture Basics

Own each capture session in a dedicated controller and serialize configuration, startRunning(), and stopRunning() on the same non-main executor. Never mix main-actor configuration with detached start/stop tasks: beginConfiguration()/commitConfiguration() and session state changes must not race. The representable view only displays the preview.

Minimal Camera Manager

Load Camera Capture for the serialized-controller pattern, photo/video delegates, focus, torch, orientation, and scanning. The critical lifecycle is:

Request access outside the session configuration transaction.
On the capture executor, call beginConfiguration() and immediately install defer { commitConfiguration() } so every early exit balances the transaction.
Add inputs and outputs only after canAddInput/canAddOutput checks.
Start or stop on that same executor, then publish UI state on the main actor only after the synchronous call returns.
On failure, stop, restore a fresh session fixture, fix the configuration, and rerun authorization, background/foreground, interruption, and capture checks.

Camera Preview in SwiftUI

Wrap AVCaptureVideoPreviewLayer in a UIViewRepresentable. Override layerClass for automatic resizing:

swift

import SwiftUI
import AVFoundation
 
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) {
        if uiView.previewLayer.session !== session {
            uiView.previewLayer.session = session
        }
    }
}
 
final class PreviewView: UIView {
    override class var layerClass: AnyClass { AVCaptureVideoPreviewLayer.self }
    var previewLayer: AVCaptureVideoPreviewLayer { layer as! AVCaptureVideoPreviewLayer }
}

Using the Camera in a View

swift

struct CameraScreen: View {
    @State private var cameraManager = CameraManager()
 
    var body: some View {
        ZStack(alignment: .bottom) {
            CameraPreview(session: cameraManager.session)
                .ignoresSafeArea()
 
            Button {
                // Capture photo -- see references/camera-capture.md
            } label: {
                Circle()
                    .fill(.white)
                    .frame(width: 72, height: 72)
                    .overlay(Circle().stroke(.gray, lineWidth: 3))
            }
            .padding(.bottom)
        }
        .task {
            await cameraManager.configure()
            cameraManager.start()
        }
        .onDisappear {
            cameraManager.stop()
        }
    }
}

Always call stop() in onDisappear. A running capture session holds the camera exclusively and drains battery.

Image Loading and Display

AsyncImage for Remote Images

swift

AsyncImage(url: imageURL) { phase in
    switch phase {
    case .empty:
        ProgressView()
    case .success(let image):
        image
            .resizable()
            .scaledToFill()
    case .failure:
        Image(systemName: "photo")
            .foregroundStyle(.secondary)
    @unknown default:
        EmptyView()
    }
}
.frame(width: 200, height: 200)
.clipShape(.rect(cornerRadius: 12))

AsyncImage does not cache images across view redraws. For production apps with many images, use a dedicated image loading library or URLCache-based caching.

Downsampling Large Images

Load full-resolution photos from the library into a display-sized CGImage to avoid memory spikes. A 48MP photo can consume over 200 MB uncompressed.

swift

import ImageIO
import UIKit
 
func downsample(data: Data, to pointSize: CGSize, scale: CGFloat = UITraitCollection.current.displayScale) -> UIImage? {
    let maxDimensionInPixels = max(pointSize.width, pointSize.height) * scale
 
    let options: [CFString: Any] = [
        kCGImageSourceCreateThumbnailFromImageAlways: true,
        kCGImageSourceShouldCacheImmediately: true,
        kCGImageSourceCreateThumbnailWithTransform: true,
        kCGImageSourceThumbnailMaxPixelSize: maxDimensionInPixels
    ]
 
    guard let source = CGImageSourceCreateWithData(data as CFData, nil),
          let cgImage = CGImageSourceCreateThumbnailAtIndex(source, 0, options as CFDictionary) else {
        return nil
    }
 
    return UIImage(cgImage: cgImage)
}

Use this whenever displaying user-selected photos in lists, grids, or thumbnails. Pass the raw Data from PhotosPickerItem directly to the downsampler before creating a UIImage.

Image Rendering Modes

swift

// Original: display the image as-is with its original colors
Image("photo")
    .renderingMode(.original)
 
// Template: treat the image as a mask, colored by foregroundStyle
Image(systemName: "heart.fill")
    .renderingMode(.template)
    .foregroundStyle(.red)

Use .original for photos and artwork. Use .template for icons that should adopt the current tint color.

Common Mistakes

DON'T: Use UIImagePickerController for photo picking. DO: Use PhotosPicker (SwiftUI) or PHPickerViewController (UIKit). Why: UIImagePickerController is legacy API with limited functionality. PhotosPicker runs out-of-process, supports multi-selection, and requires no library permission for browsing.

DON'T: Request full photo library access when you only need the user to pick photos. DO: Use PhotosPicker which requires no permission, or request .readWrite and let the system handle limited access. Why: Full access is unnecessary for most pick-and-use workflows. The system's limited-library picker respects user privacy and still grants access to selected items.

DON'T: Load full-resolution images into memory for thumbnails. DO: Use CGImageSource with kCGImageSourceThumbnailMaxPixelSize to downsample. A 48MP image is over 200 MB uncompressed.

DON'T: Block the main thread loading PhotosPickerItem data. DO: Use async loadTransferable(type:) in a Task.

DON'T: Forget to stop AVCaptureSession when the view disappears. DO: Call session.stopRunning() in onDisappear or dismantleUIView.

DON'T: Assume camera access is granted without checking. DO: Check AVCaptureDevice.authorizationStatus(for: .video) and handle .denied/.restricted.

DON'T: Call session.startRunning() on the main thread. DO: Run it on the same dedicated serial executor that owns configuration and stop operations. Why: startRunning() is a synchronous blocking call that can take hundreds of milliseconds while the hardware initializes.

DON'T: Create AVCaptureSession inside a UIViewRepresentable. DO: Own the session in a separate @Observable model.

Review Checklist

[ ] PhotosPicker used instead of deprecated UIImagePickerController
[ ] Privacy descriptions in Info.plist for camera/photo library
[ ] Loading states handled for async image/video loading
[ ] Large images downsampled with CGImageSource before display
[ ] Camera session started on background thread; stopped in onDisappear
[ ] Permission denial handled with Settings deep link
[ ] AVCaptureSession owned by model, not created inside UIViewRepresentable
[ ] Media asset types and picker results are Sendable across concurrency boundaries

References

references/photokit-patterns.md — Picker patterns, media loading, HEIC handling
references/camera-capture.md — AVCaptureSession, photo/video capture, QR scanning
references/image-loading-caching.md — AsyncImage, caching, downsampling
references/av-playback.md — AVPlayer, streaming, audio

← v1.0.0 All versions

Skill v1.0.1

PhotoKit

Contents

PhotosPicker (SwiftUI, iOS 16+)

Single Selection

Multi-Selection

Media Type Filtering

Loading Selected Items with Transferable

Privacy and Permissions

Photo Library Access Levels

Checking and Requesting Photo Library Permission

Camera Permission

Handling Denied Permissions

Required Info.plist Keys

Camera Capture Basics

Minimal Camera Manager

Camera Preview in SwiftUI

Using the Camera in a View

Image Loading and Display

AsyncImage for Remote Images

Downsampling Large Images

Image Rendering Modes

Common Mistakes

Review Checklist

References