private async void ChooseCat() { adapter.Clear(); string text = Intent.GetStringExtra("user") ?? "Data not available"; var user = JsonConvert.DeserializeObject <List <User> >(text); RestClient client = new RestClient("http://marichely.me:8099/"); RestRequest request = new RestRequest("category", Method.GET); request.AddHeader("UserApiKey", user[0].ApiKey); var odgovor = client.Execute(request); try { await Task.Run(() => { IRestResponse <List <Category> > reponse = client.Execute <List <Category> >(request); foreach (var cat in reponse.Data) { sc.Post(new SendOrPostCallback(o => { adapter.Add(o as string); adapter.NotifyDataSetChanged(); catId = adapter.GetItemId(cat.Categoryid); }), cat.Name); } }); } catch (Exception e) { Console.WriteLine(e.Message); } }