UIAlertController: style alert

-(void)mostrarAviso {
    
    UIAlertController * alert=   [UIAlertController
                                  alertControllerWithTitle:NSLocalizedString(@"Título", nil)
                                  message:NSLocalizedString(@"Mensaje", nil)
                                  preferredStyle:UIAlertControllerStyleAlert];
    
    UIAlertAction* okButton = [UIAlertAction
                                actionWithTitle:NSLocalizedString(@"Ok", nil)
                                style:UIAlertActionStyleDefault
                                handler:^(UIAlertAction * action)
                                {
                                    
                                    [alert dismissViewControllerAnimated:YES completion:nil];
                                    
                                }];
    [alert addAction:okButton];
    
    [self presentViewController:alert animated:YES completion:nil];
    
}