Example project

.github/workflows/swift.yml

@@ -12,7 +12,15 @@ jobs:
     runs-on: macos-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
+    - name: List available Xcode versions
+      run: ls /Applications | grep Xcode
+    - name: Show current version of Xcode
+      run: xcodebuild -version
+    - name: Set up Xcode version
+      run: sudo xcode-select -s /Applications/Xcode_16.1.0.app/Contents/Developer
+    - name: Show current version of Xcode
+      run: xcodebuild -version
     - name: Install Bundle
       run: bundle install
     - name: Run unit tests

BackgroundTransferRevised-Example.xcodeproj/xcshareddata/xcschemes/BackgroundTransferRevised-Example.xcscheme

@@ -0,0 +1,90 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "1600"
+   version = "1.7">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "43D1CF4E2D80860C00AC1ED9"
+               BuildableName = "BackgroundTransferRevised-Example.app"
+               BlueprintName = "BackgroundTransferRevised-Example"
+               ReferencedContainer = "container:BackgroundTransferRevised-Example.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      shouldAutocreateTestPlan = "YES">
+      <Testables>
+         <TestableReference
+            skipped = "NO"
+            parallelizable = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "43D1CF5E2D80860E00AC1ED9"
+               BuildableName = "BackgroundTransferRevised-ExampleTests.xctest"
+               BlueprintName = "BackgroundTransferRevised-ExampleTests"
+               ReferencedContainer = "container:BackgroundTransferRevised-Example.xcodeproj">
+            </BuildableReference>
+         </TestableReference>
+      </Testables>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "43D1CF4E2D80860C00AC1ED9"
+            BuildableName = "BackgroundTransferRevised-Example.app"
+            BlueprintName = "BackgroundTransferRevised-Example"
+            ReferencedContainer = "container:BackgroundTransferRevised-Example.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "43D1CF4E2D80860C00AC1ED9"
+            BuildableName = "BackgroundTransferRevised-Example.app"
+            BlueprintName = "BackgroundTransferRevised-Example"
+            ReferencedContainer = "container:BackgroundTransferRevised-Example.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

BackgroundTransferRevised-Example/Application/AppDelegate.swift

@@ -0,0 +1,32 @@
+//
+//  AppDelegate.swift
+//  BackgroundTransferRevised-Example
+//
+//  Created by William Boles on 26/03/2025.
+//
+
+import UIKit
+import OSLog
+
+class AppDelegate: NSObject, UIApplicationDelegate {
+    static var shared: AppDelegate?
+
+    private var backgroundCompletionHandler: (() -> Void)?
+    private let logger = Logger(subsystem: "com.williamboles",
+                                category: "appDelegate")
+
+    // MARK: - Background
+
+    func application(_ application: UIApplication,
+                     handleEventsForBackgroundURLSession identifier: String,
+                     completionHandler: @escaping () -> Void) {
+        self.backgroundCompletionHandler = completionHandler
+    }
+
+    func backgroundDownloadsComplete() {
+        logger.info("Triggering background session completion handler")
+
+        backgroundCompletionHandler?()
+        backgroundCompletionHandler = nil
+    }
+}

BackgroundTransferRevised-Example/Application/BackgroundTransferRevised_ExampleApp.swift

@@ -0,0 +1,48 @@
+//
+//  BackgroundTransferRevised_ExampleApp.swift
+//  BackgroundTransferRevised-Example
+//
+//  Created by William Boles on 11/03/2025.
+//
+
+import SwiftUI
+import OSLog
+
+@main
+struct BackgroundTransferRevised_ExampleApp: App {
+    @Environment(\.scenePhase) private var scenePhase
+    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
+
+    private let logger = Logger(subsystem: "com.williamboles",
+                                category: "app")
+
+
+    // MARK: - Init
+
+    init() {
+        AppDelegate.shared = appDelegate
+    }
+
+    // MARK: - Scene
+
+    var body: some Scene {
+        WindowGroup {
+            let catsViewModel = CatsViewModel()
+            CatsView(viewModel: catsViewModel)
+        }
+        .onChange(of: scenePhase) { (_, newPhase) in
+            guard newPhase == .background else {
+                return
+            }
+
+            logger.info("Files will be downloaded to: \(FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].absoluteString)")
+
+//            //Exit app to test restoring app from a terminated state. Comment out to test restoring app from a suspended state.
+//            Task {
+//                logger.info("Simulating app termination by exit(0)")
+//
+//                exit(0)
+//            }
+        }
+    }
+}

BackgroundTransferRevised-Example/Application/Info.plist

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>UIBackgroundModes</key>
+	<array>
+		<string>fetch</string>
+		<string>processing</string>
+	</array>
+</dict>
+</plist>

BackgroundTransferRevised-Example/Extensions/GridItem+Layout.swift

@@ -0,0 +1,22 @@
+//
+//  GridItem+Layout.swift
+//  BackgroundTransfer-Example
+//
+//  Created by William Boles on 11/03/2025.
+//
+
+import Foundation
+import SwiftUI
+
+extension GridItem {
+
+    static func threeFlexibleColumns() -> [GridItem] {
+        let columns = [
+            GridItem(.flexible()),
+            GridItem(.flexible()),
+            GridItem(.flexible()),
+        ]
+
+        return columns
+    }
+}

BackgroundTransferRevised-Example/Features/Cats/CatsView.swift

@@ -0,0 +1,70 @@
+//
+//  ContentView.swift
+//  BackgroundTransferRevised-Example
+//
+//  Created by William Boles on 11/03/2025.
+//
+
+import SwiftUI
+
+struct CatsView: View {
+    @StateObject var viewModel: CatsViewModel
+
+    // MARK: - View
+
+    var body: some View {
+        NavigationStack {
+            VStack {
+                switch viewModel.state {
+                case .empty:
+                    Text("We have no cats to show you! 🙀")
+                case .retrieving:
+                    ProgressView("Retrieving Cats! 😺")
+                case .retrieved(let cats):
+                    GeometryReader { geometryReader in
+                        let columns = GridItem.threeFlexibleColumns()
+                        let sideLength = geometryReader.size.width / CGFloat(columns.count)
+                        ScrollView {
+                            LazyVGrid(columns: columns, alignment: .center, spacing: 4) {
+                                ForEach(cats) { catViewModel in
+                                    CatImageCell(viewModel: catViewModel)
+                                        .frame(width: sideLength, height: sideLength)
+                                        .task {
+                                            await catViewModel.loadImage()
+                                        }
+                                }
+                            }
+                        }
+                    }
+                case .failed:
+                    Text("Failed to retrieve Cats! 😿")
+                }
+            }
+            .padding()
+            .navigationTitle("Cats 😻")
+        }
+        .task {
+            await viewModel.retrieveCats()
+        }
+    }
+}
+
+struct CatImageCell: View {
+    @StateObject var viewModel: CatViewModel
+
+    // MARK: - View
+
+    var body: some View {
+        switch viewModel.state {
+        case .empty:
+            Image(systemName: "photo")
+        case .retrieving:
+            ProgressView()
+        case .retrieved(let image):
+            image.resizable()
+                .aspectRatio(contentMode: .fill)
+                .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity)
+                .clipped()
+        }
+    }
+}