ios - viewWillAppear、viewDidAppear 未使用 pushViewController 调用

Question

NewViewController_iPhone *newViewController = [[NewViewController_iPhone alloc] initWithNibName:@"NewViewController_iPhone" bundle:nil];


[self.navigationController pushViewController:newViewController animated:YES];

viewWillAppear:并且viewDidAppear:没有被调用NewViewController_iPhone。为什么不？