protected override void OnCreate(Bundle savedInstanceState) { base.OnCreate(savedInstanceState); // Set our view from the "main" layout resource SetContentView(Resource.Layout.activity_main); Button btnLock = FindViewById <Button>(Resource.Id.buttonLock); Button btnUnlock = FindViewById <Button>(Resource.Id.buttonUnlock); RestClientService client = new RestClientService(); GetLocationPermissionAsync(); btnLock.Click += (sender, e) => { string response = client.SendLockRequest(); if (!string.IsNullOrEmpty(response)) { Toast.MakeText(this, response, ToastLength.Short).Show(); } }; btnUnlock.Click += (sender, e) => { string response = client.SendUnlockRequest(); if (!string.IsNullOrEmpty(response)) { Toast.MakeText(this, response, ToastLength.Short).Show(); } }; }