[AltStore] Extends background fetch time until finished refreshing apps

Plays silent audio in background

AltStore.xcodeproj/project.pbxproj

@@ -94,6 +94,8 @@
 		BF770E5422BC044E002A40FE /* AppOperationContext.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF770E5322BC044E002A40FE /* AppOperationContext.swift */; };
 		BF770E5622BC3C03002A40FE /* Server.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF770E5522BC3C02002A40FE /* Server.swift */; };
 		BF770E5822BC3D0F002A40FE /* OperationGroup.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF770E5722BC3D0F002A40FE /* OperationGroup.swift */; };
+		BF770E6722BD57C4002A40FE /* BackgroundTaskManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF770E6622BD57C3002A40FE /* BackgroundTaskManager.swift */; };
+		BF770E6922BD57DD002A40FE /* Silence.m4a in Resources */ = {isa = PBXBuildFile; fileRef = BF770E6822BD57DD002A40FE /* Silence.m4a */; };
 		BF7B9EF322B82B1F0042C873 /* FetchAppsOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF7B9EF222B82B1F0042C873 /* FetchAppsOperation.swift */; };
 		BF9B63C6229DD44E002F0A62 /* AltSign.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = BF9B63C5229DD44D002F0A62 /* AltSign.framework */; };
 		BFB11692229322E400BB457C /* DatabaseManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = BFB11691229322E400BB457C /* DatabaseManager.swift */; };
@@ -319,6 +321,8 @@
 		BF770E5322BC044E002A40FE /* AppOperationContext.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppOperationContext.swift; sourceTree = "<group>"; };
 		BF770E5522BC3C02002A40FE /* Server.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Server.swift; sourceTree = "<group>"; };
 		BF770E5722BC3D0F002A40FE /* OperationGroup.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OperationGroup.swift; sourceTree = "<group>"; };
+		BF770E6622BD57C3002A40FE /* BackgroundTaskManager.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = BackgroundTaskManager.swift; sourceTree = "<group>"; };
+		BF770E6822BD57DD002A40FE /* Silence.m4a */ = {isa = PBXFileReference; lastKnownFileType = file; path = Silence.m4a; sourceTree = "<group>"; };
 		BF7B9EF222B82B1F0042C873 /* FetchAppsOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FetchAppsOperation.swift; sourceTree = "<group>"; };
 		BF9B63C5229DD44D002F0A62 /* AltSign.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = AltSign.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		BFB11691229322E400BB457C /* DatabaseManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DatabaseManager.swift; sourceTree = "<group>"; };
@@ -742,6 +746,7 @@
 				BFD2478B2284C4C300981D42 /* AppIconImageView.swift */,
 				BFD2478E2284C8F900981D42 /* Button.swift */,
 				BF43002D22A714AF0051E2BC /* Keychain.swift */,
+				BF770E6622BD57C3002A40FE /* BackgroundTaskManager.swift */,
 			);
 			path = Components;
 			sourceTree = "<group>";
@@ -751,6 +756,7 @@
 			children = (
 				BFB1169C22932DB100BB457C /* Apps.json */,
 				BFD247762284B9A700981D42 /* Assets.xcassets */,
+				BF770E6822BD57DD002A40FE /* Silence.m4a */,
 			);
 			path = Resources;
 			sourceTree = "<group>";
@@ -1040,6 +1046,7 @@
 			files = (
 				BFB1169D22932DB100BB457C /* Apps.json in Resources */,
 				BFD2477A2284B9A700981D42 /* LaunchScreen.storyboard in Resources */,
+				BF770E6922BD57DD002A40FE /* Silence.m4a in Resources */,
 				BFD247772284B9A700981D42 /* Assets.xcassets in Resources */,
 				BFD247752284B9A500981D42 /* Main.storyboard in Resources */,
 				BFE6325A22A83BEB00F30809 /* Authentication.storyboard in Resources */,
@@ -1205,6 +1212,7 @@
 				BFD247702284B9A500981D42 /* AppsViewController.swift in Sources */,
 				BFDB6A0B22AAEDB7007EA6D6 /* Operation.swift in Sources */,
 				BFB116A022933DEB00BB457C /* UpdatesViewController.swift in Sources */,
+				BF770E6722BD57C4002A40FE /* BackgroundTaskManager.swift in Sources */,
 				BFBBE2DD22931B20002097FA /* AltStore.xcdatamodeld in Sources */,
 				BFE6325C22A83C0100F30809 /* AuthenticationViewController.swift in Sources */,
 				BFB1169B2293274D00BB457C /* JSONDecoder+ManagedObjectContext.swift in Sources */,

AltStore/AppDelegate.swift

@@ -91,6 +91,12 @@ extension AppDelegate
             }
         }
         
+        BackgroundTaskManager.shared.performExtendedBackgroundTask { (taskResult, taskCompletionHandler) in
+            if let error = taskResult.error
+            {
+                print("Error starting extended background task.", error)
+            }
+            
             // Wait a few seconds so we have a chance to discover nearby AltServers.
             DispatchQueue.main.asyncAfter(deadline: .now() + 3.0) {
                 
@@ -142,6 +148,8 @@ extension AppDelegate
                     case .failure: completionHandler(.failed)
                     case .success: completionHandler(.newData)
                     }
+                    
+                    taskCompletionHandler()
                 }
                 
                 let group = AppManager.shared.refresh(installedApps, presentingViewController: nil)
@@ -170,3 +178,4 @@ extension AppDelegate
             }
         }
     }
+}

AltStore/Components/BackgroundTaskManager.swift

@@ -0,0 +1,102 @@
+//
+//  BackgroundTaskManager.swift
+//  AltStore
+//
+//  Created by Riley Testut on 6/19/19.
+//  Copyright © 2019 Riley Testut. All rights reserved.
+//
+
+import AVFoundation
+
+class BackgroundTaskManager
+{
+    static let shared = BackgroundTaskManager()
+    
+    private var isPlaying = false
+    
+    private let audioEngine: AVAudioEngine
+    private let player: AVAudioPlayerNode
+    private let audioFile: AVAudioFile
+    
+    private let audioEngineQueue: DispatchQueue
+    
+    private init()
+    {
+        self.audioEngine = AVAudioEngine()
+        self.audioEngine.mainMixerNode.outputVolume = 0.0
+        
+        self.player = AVAudioPlayerNode()
+        self.audioEngine.attach(self.player)
+        
+        do
+        {
+            let audioFileURL = Bundle.main.url(forResource: "Silence", withExtension: "m4a")!
+            
+            self.audioFile = try AVAudioFile(forReading: audioFileURL)
+            self.audioEngine.connect(self.player, to: self.audioEngine.mainMixerNode, format: self.audioFile.processingFormat)
+        }
+        catch
+        {
+            fatalError("Error. \(error)")
+        }
+        
+        self.audioEngineQueue = DispatchQueue(label: "com.altstore.BackgroundTaskManager")
+    }
+}
+
+extension BackgroundTaskManager
+{
+    func performExtendedBackgroundTask(taskHandler: @escaping ((Result<Void, Error>, @escaping () -> Void) -> Void))
+    {
+        func finish()
+        {
+            self.player.stop()
+            self.audioEngine.stop()
+            
+            self.isPlaying = false
+        }
+        
+        self.audioEngineQueue.async {
+            do
+            {
+                try AVAudioSession.sharedInstance().setCategory(.playback, options: .mixWithOthers)
+                try AVAudioSession.sharedInstance().setActive(true)
+                
+                // Schedule audio file buffers.
+                self.scheduleAudioFile()
+                self.scheduleAudioFile()
+                
+                let outputFormat = self.audioEngine.outputNode.outputFormat(forBus: 0)
+                self.audioEngine.connect(self.audioEngine.mainMixerNode, to: self.audioEngine.outputNode, format: outputFormat)
+                
+                try self.audioEngine.start()
+                self.player.play()
+                
+                self.isPlaying = true
+                
+                taskHandler(.success(())) {
+                    finish()
+                }
+            }
+            catch
+            {
+                taskHandler(.failure(error)) {
+                    finish()
+                }
+            }
+        }
+    }
+}
+
+private extension BackgroundTaskManager
+{
+    func scheduleAudioFile()
+    {
+        self.player.scheduleFile(self.audioFile, at: nil) {
+            self.audioEngineQueue.async {
+                guard self.isPlaying else { return }
+                self.scheduleAudioFile()
+            }
+        }
+    }
+}

AltStore/Info.plist

@@ -43,6 +43,7 @@
 	<true/>
 	<key>UIBackgroundModes</key>
 	<array>
+		<string>audio</string>
 		<string>fetch</string>
 	</array>
 	<key>UILaunchStoryboardName</key>