Fix iOS takeSnapshot not working (#83)

Author: Antonimo

ios/Classes/SwiftFlutterVlcPlayerPlugin.swift

@@ -121,7 +121,7 @@ public class VLCView: NSObject, FlutterPlatformView {
                     let byteArray = (image ?? UIImage()).pngData()
 
                     result([
-                        "snapshot": byteArray
+                        "snapshot": byteArray?.base64EncodedString()
                     ])
                     return
 
@@ -151,6 +151,9 @@ public class VLCView: NSObject, FlutterPlatformView {
                     result(FlutterMethodNotImplemented)
                     return
                 }
+            } else {
+                result(FlutterMethodNotImplemented)
+                return
             }
 
         })

lib/flutter_vlc_player.dart

@@ -366,7 +366,7 @@ class VlcPlayerController {
   }
 
   Future<Uint8List> takeSnapshot() async {
-    var result = await _methodChannel.invokeMethod("getSnapshot");
+    var result = await _methodChannel.invokeMethod("getSnapshot", {'getSnapShot': ''});
     var base64String = result['snapshot'];
     Uint8List imageBytes = CryptoUtils.base64StringToBytes(base64String);
     return imageBytes;