iOS统一比例子视图与superview

Question

I have an app that allows a user to drag views onto the screen in multiple orientations. So lets say i'm in portrait mode and my superview is 768x1024. Lets say I drag 10 different items onto that superview. These items are scaled, rotated, etc. Then I rotate the device and my superview shrinks down to 576x768. How do I get all of my subviews to maintain their position and transform relative to the new smaller size? So in essence my superview and all of its subviews should look exactly as they did while in portrait, except everything has been scaled down.

And also, what if im in landscape and everything is "shrunk" down and then I drag another view on and shrink it down to fit well. I would need that new view to scale up in proper place and size when the device is rotated back into portrait

Answer 1

The easiest thing to do here is to use the transform property of your view. In this case, you'd prevent the view from auto-resizing on rotation, and use something like your view controller's willAnimateRotationToInterfaceOrientation:duration: method to set a transform on your superview. You can create a transform with CGAffineTransformMakeScale that will scale up or down all of your content; you'll probably want one for landscape and just use a nil transform for portrait (or vice-versa).

This will complicate dragging new views into your superview, since it's transformed, but once you've got views in there, they should behave correctly when resizing. For new views, you'll have to compute (perhaps using convertRect:fromView: method of UIView) what a rect will be once you add a new subview.

Answer 2

You can also override your view's layoutSubviews() directly and assign your subview's transforms based on your view's dimension. This way, you can still get the benefits of using Auto Layout with your view and potentially other sibling UI items, while you customize subview's frames and/or transforms manually without Auto Layout.