feat(ios): files sending

ios/Classes/StreamHandler/ConnectedDeviceStreamHandler.swift

@@ -0,0 +1,39 @@
+import Flutter
+import MultipeerConnectivity
+
+class ConnectedDeviceStreamHandler: NSObject, FlutterStreamHandler {
+    private var eventSink: FlutterEventSink?
+    private var timer : Timer?
+
+    func onListen(withArguments arguments: Any?, eventSink: @escaping FlutterEventSink) -> FlutterError? {
+        let deviceId = arguments as! String
+        self.eventSink = eventSink
+        startSendingUpdates(deviceId: deviceId)
+        return nil
+    }
+
+    func onCancel(withArguments arguments: Any?) -> FlutterError? {
+        stopSendingUpdates()
+        eventSink = nil
+        return nil
+    }
+
+    func startSendingUpdates(deviceId:String) {
+        self.timer = Timer.scheduledTimer(withTimeInterval: 2.0, repeats: true) { [weak self] _ in
+            guard let self = self else { return }
+            var result: String?
+            if let device = NearbyDevicesStore.instance.find(for: deviceId),
+               let session = device.session {
+                if (session.state == MCSessionState.connected) {
+                    result = device.toDartFormat()
+                }
+            }
+            self.eventSink?(result)
+        }
+    }
+
+    func stopSendingUpdates() {
+        self.timer?.invalidate()
+        self.timer = nil
+    }
+}