动画“幻灯片”iOS UIView但关联的子视图不会移动

Question

I'm having a problem with what I thought was a simple UIView slide animation from a UINavigationBar. I have a UIView with a UIButton and I would like to simulate a slide down/up effect from the Navigation Bar by animating the View height. The problem is the View animates but any SubViews eg UIButton stay fixed.

I'm coding in Xamarin (C#) but I'm sure it's simple enough to read for Objective-C coders

if (_menuView == null)
{
   // set initial frame
   _menuView = new MenuView{Frame = Window.Frame};

   // store original "expanded" height for later
   _expandedMenuHeight = _menuView.Frame.Height;

   // set the frame to underneath the NavigationBar
   var frame = ((UINavigationController)Window.RootViewController).NavigationBar.Frame;
   var y = frame.Bottom;

   // Add to Window View
   menuView.Frame = new RectangleF(_menuView.Frame.X,y,_menuView.Frame.Width,0);
   Window.Add(_menuView);
 }

 // Toggle View Height - if collapsed, expand, if expanded, collapse
 var height = _menuView.Frame.Height == 0 ? _expandedMenuHeight : 0;

 // Animate the height
 UIView.Transition (_menuView,0.2,UIViewAnimationOptions.CurveEaseIn |   UIViewAnimationOptions.LayoutSubviews,() => {
 _menuView.Frame = new RectangleF(0,_menuView.Frame.Y,_menuView.Frame.Width,height); },null);

Any pointers are greatly appreciated!

Answer 1

I am not so clear with Xamarin. But in objectiveC, you could use,

view.clipsToBounds = YES;

So when you are trying to reduce the height the subviews would also be hidden.