Placing and Moving Views on Rotation (UIView)

Question

What's the "correct" way of exactly placing and moving views when an app rotates? That is, how can I have fine-grained control of the position, size, and reflow of my views when the UI rotates from portrait to landscape orientation (or vice-versa)? I think my two options are:

1. Use two superviews (portrait and landscape). On rotation: toggle between them.
2. Use one superview. On rotation: change each subview's frame, bounds, and center properties.

If you have two views with distinct enough layouts and elements, then the first way might be good enough. If your two views are essentially the same thing sized for different orientations, the second way is probably a better way to do it using only one view.

I suspect the former could be done with IB and the latter should be done programmatically.

Answer 1

To have fine-grained control over the position and size of your subviews when the iPhone rotates, change the frame of the subviews in the UIViewController method willAnimateRotationToInterfaceOrientation:duration:. This method is called within an animation block, so all the changes to your subviews' frames that you make inside of it are animated.

- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
    if (UIInterfaceOrientationIsPortrait(toInterfaceOrientation)) {
        // Portrait frames
        self.subviewA.frame = CGRectMake(x, y, width, height);
        self.subviewB.frame = CGRectMake(x, y, width, height);
        self.subviewC.frame = CGRectMake(x, y, width, height);
    } else {
        // Landscape frames
        self.subviewA.frame = CGRectMake(x, y, width, height);
        self.subviewB.frame = CGRectMake(x, y, width, height);
        self.subviewC.frame = CGRectMake(x, y, width, height);
    }
}