HTTP Request in LocationManager.DidDetermineState - ios

Question

I have written IBeacon App and my goal is to send Http request when the app is in background. I use the DidDetermineState event to determine the entrance/leave of a region. The thing is that when the event is called Http request unexpectedly stops somewhere. No exception is thrown and can not finish the request.
The strange thing is that the call stops randomly on different lines.
[Export ("locationManager:didDetermineState:forRegion:")]
public void DidDetermineState (CLLocationManager manager, CLRegionState state, CLRegion region)
{
string message = "";
if (state == CLRegionState.Inside) {
message = "Inside";
var url = String.Format ("{0}About", "https://myAPIURl/");
try {
var _httpClient = new HttpClient ();
_httpClient.Timeout = TimeSpan.FromMilliseconds (30000);
lock (_httpClient) {
try {
var getResult = _httpClient.GetAsync (url).Result;
if (getResult.IsSuccessStatusCode) {
var contentString = getResult.Content.ReadAsStringAsync ().Result;
var contentObject = JsonConvert.DeserializeObject<AboutUsModel> (contentString);
message = "result ok";
}
}
//ncrunch: no coverage start
catch (Exception e) {
message = e.Message;
}
}
} catch (Exception ex) {
message = ex.Message;
}
}
if (state == CLRegionState.Outside) {
message = "Outside";
}
}
P.S The request is successfully sent when the app is in foreground mode.
Any help is appreciated!

Answer 1

Apple only gives you about five seconds of background execution time after getting a beacon callback in the background. If the web service does not respond quickly enough, the app will simply suspend.
A typical way to solve this problem is to request extra background running time -- you can get up to 3 minutes worth just by asking. I wrote a blog post about the process here. The blog post is specifically about extending background ranging time, but the same technique applies to getting extended time for web service callbacks.