ScrollView as subview does not respect frame boundaries

I have a UIScrollView (managed by a view controller) which I am using both full screen and as a subview. The full screen version wo开发者_开发问答rks fine - the subview does not.

The subview is positioned so that it takes up about the bottom half of the screen, with a small - 20 pixels or so - margin at the bottom.

Initially it displays in the correct position but overwrites the bottom margin - even though the scrollview's frame is set to leave the margin.

When I scroll the view up by dragging it, the whole view moves upwards and obscures the top of the window. The frame stops moving when it hits the navigation bar at the top and starts scrolling like a normal scrollview. If I scroll it enough it eventually reveals the margin at the bottom of the screen.

I am at a loss to know what to do - I've tried every spring combination I can think of. I'm now looking at subview clipping.

Images below. The first shows the scrollview on initial page load, positioned correctly aside from lower margin overwrite. The scroll view has a white background.

The second image shows it scrolled up toward the top:

The third image shows it scrolled all the way up to the top - note that the lower margin has become visible.

I'm not 100% sure on this one, but worthy the shot: my guess is you're likely not setting the Bounds property correctly on your table.

To solve this issue, the easiest way would be to set myscrollview.clipsToBounds = true.

Something is definitely wrong here. I think what happens is that you are adding the same instance of scrollview as a subview on itself. So basically what you are left with, is one instance alone. Anything you add to the "subview", is basically added on the superview, since it is the same object.

For example, this is what I think you are doing in the view controller:

//...
private UIScrollView myScrollView;
public override void ViewDidLoad()
{
    this.myScrollView = new UIScrollView();
    this.View = this.myScrollView;
    this.View.AddSubview(this.mySrcollView); // same instance
    this.myScrollView.AddSubview(aUIButton); // "aUIButton" will be added in View also, since it is the same object
}

If this is the case, it is wrong. I suggest not changing the controller's view at all. If you want to have a controller that has a fullscreen UIScrollView, just create it and add it as a subview, making sure the AutoSizesSubviews property to true.

That's my understanding at least.