UIAlertController *alertController = [UIAlertController alertControllerWithTitle:LocalizedString(@"Success")
                                                                                     message:LocalizedString(@"Example") preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *actionOk = [UIAlertAction actionWithTitle:LocalizedString(@"Ok")
                                                               style:UIAlertActionStyleDefault
                                                            handler:^(UIAlertAction *action){
                                                                [self dismissViewControllerAnimated:YES completion:^
                                                                 {
                                                                     [self performSelector:@selector(presentLogInViewController) withObject:nil];
                                                                 }];
                                                            }];
[alertController addAction:actionOk];
[self presentViewController:alertController animated:YES completion:nil];

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:LocalizedString(@"Success")
                                                                         message:LocalizedString(@"Example")
                                                                  preferredStyle:UIAlertControllerStyleAlert];

UIAlertAction *actionOk = [UIAlertAction actionWithTitle:LocalizedString(@"Ok")
                                                   style:UIAlertActionStyleDefault
                                                 handler:^(UIAlertAction *action) {
                                                      [self performSelector:@selector(presentLogInViewController) withObject:nil];
                                                 }];

[alertController addAction:actionOk];
[self presentViewController:alertController animated:YES completion:nil];

UIAlertAction* cancelAction = [UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault  handler:^(UIAlertAction * action)
                                       {
             [alertController dismissViewControllerAnimated:YES completion:nil];
                                       }];
        [alertController addAction:cancelAction];
        [self presentViewController: alertController animated:YES completion:nil];

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

    UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
       handler:^(UIAlertAction * action) {
     // here you can add the completion for when the OK button is pressed
}];
    [alert addAction:defaultAction];
    [self presentViewController:alert animated:YES completion:nil];