feat: background streaming of responses

ios/Runner/AppDelegate.swift

@@ -1,13 +1,166 @@
 import Flutter
 import UIKit
 
+// Background streaming handler class
+class BackgroundStreamingHandler: NSObject {
+    private var backgroundTask: UIBackgroundTaskIdentifier = .invalid
+    private var activeStreams: Set<String> = []
+    private var channel: FlutterMethodChannel?
+    
+    override init() {
+        super.init()
+        setupNotifications()
+    }
+    
+    func setup(with channel: FlutterMethodChannel) {
+        self.channel = channel
+    }
+    
+    private func setupNotifications() {
+        NotificationCenter.default.addObserver(
+            self,
+            selector: #selector(appDidEnterBackground),
+            name: UIApplication.didEnterBackgroundNotification,
+            object: nil
+        )
+        
+        NotificationCenter.default.addObserver(
+            self,
+            selector: #selector(appWillEnterForeground),
+            name: UIApplication.willEnterForegroundNotification,
+            object: nil
+        )
+    }
+    
+    @objc private func appDidEnterBackground() {
+        if !activeStreams.isEmpty {
+            startBackgroundTask()
+        }
+    }
+    
+    @objc private func appWillEnterForeground() {
+        endBackgroundTask()
+    }
+    
+    func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
+        switch call.method {
+        case "startBackgroundExecution":
+            if let args = call.arguments as? [String: Any],
+               let streamIds = args["streamIds"] as? [String] {
+                startBackgroundExecution(streamIds: streamIds)
+                result(nil)
+            } else {
+                result(FlutterError(code: "INVALID_ARGS", message: "Invalid arguments", details: nil))
+            }
+            
+        case "stopBackgroundExecution":
+            if let args = call.arguments as? [String: Any],
+               let streamIds = args["streamIds"] as? [String] {
+                stopBackgroundExecution(streamIds: streamIds)
+                result(nil)
+            } else {
+                result(FlutterError(code: "INVALID_ARGS", message: "Invalid arguments", details: nil))
+            }
+            
+        case "keepAlive":
+            keepAlive()
+            result(nil)
+            
+        case "saveStreamStates":
+            if let args = call.arguments as? [String: Any],
+               let states = args["states"] as? [[String: Any]] {
+                saveStreamStates(states)
+                result(nil)
+            } else {
+                result(FlutterError(code: "INVALID_ARGS", message: "Invalid arguments", details: nil))
+            }
+            
+        case "recoverStreamStates":
+            result(recoverStreamStates())
+            
+        default:
+            result(FlutterMethodNotImplemented)
+        }
+    }
+    
+    private func startBackgroundExecution(streamIds: [String]) {
+        activeStreams = Set(streamIds)
+        
+        if UIApplication.shared.applicationState == .background {
+            startBackgroundTask()
+        }
+    }
+    
+    private func stopBackgroundExecution(streamIds: [String]) {
+        streamIds.forEach { activeStreams.remove($0) }
+        
+        if activeStreams.isEmpty {
+            endBackgroundTask()
+        }
+    }
+    
+    private func startBackgroundTask() {
+        guard backgroundTask == .invalid else { return }
+        
+        backgroundTask = UIApplication.shared.beginBackgroundTask(withName: "ConduitStreaming") { [weak self] in
+            self?.endBackgroundTask()
+        }
+    }
+    
+    private func endBackgroundTask() {
+        guard backgroundTask != .invalid else { return }
+        
+        UIApplication.shared.endBackgroundTask(backgroundTask)
+        backgroundTask = .invalid
+    }
+    
+    private func keepAlive() {
+        if backgroundTask != .invalid {
+            endBackgroundTask()
+            startBackgroundTask()
+        }
+    }
+    
+    private func saveStreamStates(_ states: [[String: Any]]) {
+        UserDefaults.standard.set(states, forKey: "ConduitActiveStreams")
+    }
+    
+    private func recoverStreamStates() -> [[String: Any]] {
+        return UserDefaults.standard.array(forKey: "ConduitActiveStreams") as? [[String: Any]] ?? []
+    }
+    
+    deinit {
+        NotificationCenter.default.removeObserver(self)
+        endBackgroundTask()
+    }
+}
+
 @main
 @objc class AppDelegate: FlutterAppDelegate {
+  private var backgroundStreamingHandler: BackgroundStreamingHandler?
+  
   override func application(
     _ application: UIApplication,
     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
   ) -> Bool {
     GeneratedPluginRegistrant.register(with: self)
+    
+    // Setup background streaming handler manually
+    if let controller = window?.rootViewController as? FlutterViewController {
+      let channel = FlutterMethodChannel(
+        name: "conduit/background_streaming",
+        binaryMessenger: controller.binaryMessenger
+      )
+      
+      backgroundStreamingHandler = BackgroundStreamingHandler()
+      backgroundStreamingHandler?.setup(with: channel)
+      
+      // Register method call handler
+      channel.setMethodCallHandler { [weak self] (call, result) in
+        self?.backgroundStreamingHandler?.handle(call, result: result)
+      }
+    }
+    
     return super.application(application, didFinishLaunchingWithOptions: launchOptions)
   }
 }