模态视图

- (IBAction)login:(id)sender {
    UIStoryboard* mainStoryboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
    UIViewController *LoginViewController = [mainStoryboard instantiateViewControllerWithIdentifier:@"firstview"];
    
    LoginViewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    [self presentViewController:LoginViewController animated:YES completion:^{
        NSLog(@"Present Modal View");
    }];
    
}