Hey Andrea,
I read the articles (at my best!). The question is where to insert the two statements:
HttpsClientHandlerService handler = new HttpsClientHandlerService();
HttpClient client = new HttpClient(handler.GetPlatformMessageHandler());
considering the statement of the example (OnApiCallClicked):
HttpResponseMessage response = await _httpClient.GetAsync(“api/messages/protected”);
Because now _httpClient is a parameter of MainPage
Fabrizio