uialertcontroller example objective c

UIAlertController* alert = [UIAlertController alertControllerWithTitle:@"My Alert"
	message:@"This is an alert."
	preferredStyle:UIAlertControllerStyleAlert];

UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
	handler:^(UIAlertAction * action) {}];

[alert addAction:defaultAction];
[self presentViewController:alert animated:YES completion:nil];