超视图转换时防止子视图转换

Question

I have the following set up. I have a UIView called parentView that holds a UIView called childView . parentView can be rotated and resized using some touch gestures which need to be on the parentView . childView has some drawing code in its drawRect method which needs to updated as the parentView is transformed.

I am noticing when I transform the parentView (scale or rotate), childView automatically gets transformed as well. Problem with this is, while I do want the rotate transform to be initiated on the childView , I don't want it to be scale, I'd rather execute its drawing code.

So my question is, what is a good way to handle this situation? I notice when I call " setNeedsDisplay " on my childView after parentView is transformed, it doesn't get executed.

Answer 1

Don't transform the parent view; transform a sibling of the child view.

In other words, your current set up looks like this:

transformedView
    childView

Instead, do this:

parentView
    transformedView
    childView

That way the transformation won't affect the child.

Answer 2

I had to apply the rotation to the parentView , and then set the bounds property of parentView and childView to resize it. Then I was able to redraw the childView in drawRect successfully. Bottom line is though I think if you set a transform on a childs superview, I think you're stuck having to live with it in its subviews. I tried setting the transforms separately and all of the timing of the transforms got screwed up. The above situation from Brent might also come in handy for certain situations.