// add child viewController添加子视图
UIViewController* controller = [self.storyboard instantiateViewControllerWithIdentifier:@"test"];
[self addChildViewController:controller];
controller.view.frame = CGRectMake(0, 44, 320, 320);
[self.view addSubview:controller.view];
[controller didMoveToParentViewController:self];
// remove child viewController删除子视图
UIViewController *vc = [self.childViewControllers lastObject];
[vc.view removeFromSuperview];
[vc removeFromParentViewController];
