flutter application automatically updates

Man of few words said, directly on the code:

package_info: ^0.4.0+16
  path_provider: ^1.6.5
  open_file: ^3.0.1
  url_launcher: ^5.4.2

_Update () the async {
     IF (Platform.isIOS) {
 //       String URL = 
//           '? ITMS-Apps: MT = //itunes.apple.com/cn/app/id414478124. 8'; // this is the address of the micro-letter , the address to be replaced when their application 
//       IF (the await canLaunch (URL)) { 
//         the await Launch (URL); 
//       } the else { 
//         the throw 'Could Not Launch $ URL'; 
//       } 
    } the else  IF (Platform.isAndroid) {
      URL String = HttpUtils.VERSION_URL + 'App-release.apk' ;
       the try {
         // / store files created 
        Directory = StorageDir the await getExternalStorageDirectory ();
        String storagePath = storageDir.path;
        File _apkFile = await downloadAndroid(storagePath,url);
        OpenFile.open("${storagePath}/app-release.apk");
      } catch (e) {
        print ( '$ {e}' );
      }
    }
  }

  // / download update packages Andrews 
  Future <File> downloadAndroid (StoragePath String, String URL) the async {
    File file = new File('$storagePath/app-release.apk');
    if (!file.existsSync()) {
      file.createSync();
    }
    try {
      print("-------------333333333333");
      Function tr = throttle((List args){
        print("-----------------------6666");
        int count = args[0];
        int total = args[1];
        double radio = count/total;
        String str = (_progress_val*100).toInt().toString();
        setState(() {
          _progress_val = radio;
          _progress = "download progress: STR $ {}%" ;
        });
      }, 500 );
       // / downloading request to initiate 
      the Response Response = the await Dio () GET (URL,.
          onReceiveProgress: (int count,int total){
//            tr([count,total]);
            double radio = count/total;
            String str = (_progress_val*100).toInt().toString();
            setState(() {
              _progress_val = radio;
              _progress = "download progress: STR $ {}%" ;
            });
          },
          options: Options(
            responseType: ResponseType.bytes,
            followRedirects: false,
          ));
      file.writeAsBytesSync(response.data);
      return file;
    } catch (e) {
      print (e);
    }
  }