source-code

source-code/ALTs/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.sync {
+            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()
+            }
+        }
+    }
+}