Add weekly background Kyoto CBF sync task (#352)

Author: Aniket-pd

BDKSwiftExampleWallet/App/BDKSwiftExampleWalletApp.swift

@@ -6,13 +6,20 @@
 //
 
 import BitcoinDevKit
+import BackgroundTasks
 import SwiftUI
 
 @main
 struct BDKSwiftExampleWalletApp: App {
     @AppStorage("isOnboarding") var isOnboarding: Bool = true
     @State private var navigationPath = NavigationPath()
     @State private var refreshTrigger = UUID()
+    @Environment(\.scenePhase) private var scenePhase
+
+    init() {
+        BackgroundCBFSyncTask.register()
+        BackgroundCBFSyncTask.schedule()
+    }
 
     var body: some Scene {
         WindowGroup {
@@ -30,6 +37,11 @@ struct BDKSwiftExampleWalletApp: App {
                 BDKClient.live.setNeedsFullScan(true)
                 navigationPath = NavigationPath()
             }
+            .onChange(of: scenePhase) { _, newValue in
+                if newValue == .background {
+                    BackgroundCBFSyncTask.schedule()
+                }
+            }
         }
     }
 }
@@ -42,3 +54,69 @@ extension BDKSwiftExampleWalletApp {
         return (try? KeyClient.live.getBackupInfo()) != nil
     }
 }
+
+private enum BackgroundCBFSyncTask {
+    static let identifier = "com.bitcoindevkit.bdkswiftexamplewallet.cbf-sync"
+    private static let minimumInterval: TimeInterval = 60 * 60 * 24 * 7
+
+    static func register() {
+        BGTaskScheduler.shared.register(
+            forTaskWithIdentifier: identifier,
+            using: nil
+        ) { task in
+            guard let processingTask = task as? BGProcessingTask else {
+                task.setTaskCompleted(success: false)
+                return
+            }
+            handle(processingTask)
+        }
+    }
+
+    static func schedule() {
+        let request = BGProcessingTaskRequest(identifier: identifier)
+        request.requiresNetworkConnectivity = true
+        request.requiresExternalPower = true
+        request.earliestBeginDate = Date(timeIntervalSinceNow: minimumInterval)
+
+        do {
+            try BGTaskScheduler.shared.submit(request)
+        } catch {
+            print("[BackgroundCBF] Failed to schedule task: \(error)")
+        }
+    }
+
+    private static func handle(_ task: BGProcessingTask) {
+        schedule()
+
+        let syncTask = Task.detached(priority: .background) {
+            do {
+                try await runKyotoSync()
+                task.setTaskCompleted(success: true)
+            } catch {
+                print("[BackgroundCBF] Background sync failed: \(error)")
+                task.setTaskCompleted(success: false)
+            }
+        }
+
+        task.expirationHandler = {
+            syncTask.cancel()
+        }
+    }
+
+    private static func runKyotoSync() async throws {
+        let bdkClient = BDKClient.live
+
+        guard (try? bdkClient.getBackupInfo()) != nil else {
+            return
+        }
+
+        try bdkClient.loadWallet()
+
+        guard bdkClient.getClientType() == .kyoto else {
+            return
+        }
+
+        let inspector = WalletSyncScriptInspector(updateProgress: { _, _ in })
+        try await bdkClient.syncWithInspector(inspector)
+    }
+}

BDKSwiftExampleWallet/Info.plist

@@ -2,9 +2,17 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
+	<key>BGTaskSchedulerPermittedIdentifiers</key>
+	<array>
+		<string>com.bitcoindevkit.bdkswiftexamplewallet.cbf-sync</string>
+	</array>
 	<key>ITSAppUsesNonExemptEncryption</key>
 	<false/>
 	<key>NSPasteboardUsageDescription</key>
 	<string>"To allow users to copy and paste text between the app and other apps"</string>
+	<key>UIBackgroundModes</key>
+	<array>
+		<string>processing</string>
+	</array>
 </dict>
 </plist>

BDKSwiftExampleWallet/Service/Key Service/KeyService.swift

@@ -16,7 +16,7 @@ private struct KeyService {
         let keychain = Keychain(service: "com.matthewramsden.bdkswiftexamplewallet.testservice")
             .label(Bundle.main.displayName)
             .synchronizable(false)
-            .accessibility(.whenUnlocked)
+            .accessibility(.afterFirstUnlock)
         self.keychain = keychain
     }