Hello everyone. There is a problem that has bothered me for a long time recently. I have two controllers, let's call them controllerA and controllerB. When I click some button in controllerA, I want to push controllerB into the navigation. Besides, I need some UITextField get the focus automatically when I enter controllerB. The code is very simple. @implementation ControllerA -(void)p_addClick:(id)sender { ControllerB *controllerB = [[ControllerB alloc] init]; [self.navigationController pushViewController:controllerB animated:YES]; } @end @implementation ControllerB - (void)viewDidLoad { [super viewDidLoad]; self.view.backgroundColor = [UIColor grayColor]; _editorView = [[UITextField alloc] init]; _editorView.placeholder = @"test"; _editorView.clearButtonMode = UITextFieldViewModeWhileEditing; _editorView.frame = CGRectMake(200, 200, 100, 100); [_editorView becomeFirstResponder]; /* This is the point code */ [self.view addSubview:_editorView]; } @end If I code like this, then controllerB will first come out a little from the right of the screen, then go back, and finally show completely. It seems that the screen is shaking a little. I test on some OS and found that only 16.0 and above models will behave like this, 15.5 and below is very smooth. I think this seems to be a system bug, but don't know how to fix it. I try to call becomeFirstResponder in the method of viewDidAppear in controllerB, then everything is OK. But there's many cases like this. Changing every controller seems not elegant enough.