Question

I have a UIWebView. Using something like this:

http://blog.evandavey.com/2009/02/how-to-make-uiwebview-transparent.html

.. I have made the UIWebView transparent. I now need to be able to pass though touches on the webview to the view below, but only on a rectangular portion of the web view.

So, imagine the webview is a square, and it has a square area in the centre which must pass-thru touches to the view below.

Is there a way to do this?

Answer 1

This is a more specific form of hitTest manipulation.

First, create a subclass of UIView. I called mine ViewWithHole.

In its header, define a property for a UIView that will be the hole through the outer view. Make this an IBOutlet.

@property (retain) IBOutlet UIView *holeView;

Then override hitTest. If the point is returns a hit within the hole, return that. Otherwise return what it usually would.

- (UIView*) hitTest:(CGPoint)point withEvent:(UIEvent *)event;
{
    CGPoint pointInHole = [self convertPoint:point toView:self.holeView];
    UIView *viewInHole = [self.holeView hitTest:pointInHole withEvent:event];

    if (viewInHole)
        return viewInHole;
    else
        return [super hitTest:point withEvent:event];
}

In Interface Builder, or programmatically, place a ViewWithHole. Put a UIView and a UIWebView within it, in that order. Make the UIView the holeView of the ViewWithHole.

The holeView can itself be interactive, or you can put any number of interactive views within it. Here, I put a few standard views in there to make sure they work. Any taps on within the hole will be sent to it and its subviews, not the UIWebView on top. Any taps outside the holeView will be received by the UIWebView as usual.

You can have any number and type of views displayed in front of the hole; all that matters is that the holeView is properly connected.