public Task <List <User> > CheckUsersInGroupPresence(GroupChannel channel) { var tcs = new TaskCompletionSource <List <User> >(); if (channel == null) { tcs.TrySetCanceled(); return(tcs.Task); } channel.Refresh((e) => { if (e != null) { tcs.TrySetCanceled(); } else { tcs.TrySetResult(channel.Members); } }); Debug.WriteLine("UpdateUsers Presence"); return(tcs.Task); }