[IOS] interceptor onError is not triggered only when losing connectivity

[amrosama2020]

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• [Yes] I have searched for a similar issue in the project and found none

Issue Info

Info	Value
Platform Name	ios
Platform Version	All
Dio Version	2.1.13
Android Studio / Xcode Version	Xcode 10.2.1
Repro rate	all the time (100%)
Repro with our demo prj	Can't reproduce because response is too fast
Demo project link	Can prepare it

Issue Description and Steps

Issue is that the interceptor onError doesn't trigger in IOS in the following scenario:

1. initiate a slow request
2. disable/lose connectivity (e.g. close mobile network)

Interceptor onRequest, onResponse, and onError normally work with regular scenarios on all platforms, but in IOS onError is not triggered only when losing connectivity after sending the request.

Interceptor is setup like this:

var client = Dio();
    client.interceptors
        .add(InterceptorsWrapper(onError: (DioError e) {
      // Do something with response error
      // if (e.error is HttpException || e.error is SocketException)
      //   e.message = "Connection Failed, Please check your internet connection";
      return e; //continue
    }));

I tried placing breakpoints in all catch statements in dio library but none fire on losing connection.

[zk-luke]

I have encountered a similar problem to you.
The interceptor can not intercept DioErrorType.CANCEL either.
For now, I solve the problem like this:

try {
      Response res = await _dio.request(
        path,
        data: data,
        queryParameters: queryParameters,
        options: Options(method: method),
      );
      return res.data;
    } catch (e) {
	
      //if e.type == DioErrorType.CONNECT_TIMEOUT
      //you can handle the error at here
      
      return {};
    }

[bishopmorton]

in adapter.dart.
it makes sense to work around all awaits, not only _httpClient.openUrl...

await request.addStream(requestStream).timeout(Duration(milliseconds:options.connectTimeout));
}

HttpClientResponse responseStream = await request.close().timeout(Duration(milliseconds:options.connectTimeout));

^^^ it helps on iOS to finally start getting connect timeouts

[amrosama2020]

I ended up adding a timeout but still users with disconnected network will have to wait for the timeout to finish before getting an error.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If this is still an issue, please make sure it is up to date and if so, add a comment that this is still an issue to keep it open. Thank you for your contributions.

[quantela-ashutosh]

Still facing this issue.