Web service request gets stuck while switching between application in Xamarin iOS

Question

We are trying to make a call to web service (nonsecure i.e. HTTP) in Xamarin.iOS. As it is an http URL we have added NSAppTransportSecurity to bypass the secure access.

Currently, we are using HttpClient with NSUrlSessionHandler so that ATS config specified in info.plist gets applied.

client = new HttpClient(new NSUrlSessionHandler());

Problem #1

Now, the issue is whenever we are firing the web service request and after that, if we switch to a different app and come back to our app, the request gets stuck and does not return anything. if we stay on our app, it returns the response successfully.

Problem #2

In order to resolve Problem#1 issue of switching app, we tried client = new HttpClient(new CFNetworkHandler()); i.e. using CFNetworkHandler and that resolves our issue but this eventually creates another issue of accessing http URL. As we have used CFNetworkHandler , configurations related to NSAppTransportSecurity in info.plist gets ignored. As Apple Developer Document says

ATS doesn’t apply to calls your app makes to lower-level networking interfaces like the Network framework or CFNetwork.

Error that we get while calling webservice with CFNetwork is as follows and it looks like info.plist config is getting ignored

StatusCode: 505, ReasonPhrase: 'HTTP/1.1 505 HTTP Version Not Supported', Version: 1.1, Content: System.Net.Http.CFContentStream, Headers:
{
  Date: Fri, 03 Jul 2020 06:15:19 GMT
  Connection: close
  Server: Microsoft-HTTPAPI/2.0
  Content-Type: text/html; charset=us-ascii
  Content-Length: 350
}

However, on the other end,Microsoft Xamarin Says

App Transport Security does not apply to Xamarin apps using Managed HTTPClient implementations. It applies to connections using CFNetwork HTTPClient implementations or NSURLSession HTTPClient implementations only.

So, if we use NSUrlSessionHandler the request got stuck while switching app and if we use CFNetworkHandler then ATS won't allow to access the services.

ATS Configurations are as follows

1. set NSAppTransportSecurity with NSAllowsArbitraryLoads set to YES

2. set NSExceptionDomains with following parameters

   a. naaxdev.cloudapp.net

   b. NSIncludesSubdomains set to YES

   c. NSExceptionAllowsInsecureHTTPLoads set to YES

   d. NSExceptionRequiresForwardSecrecy set to NO