UIScrollView and Autoration issues - objective-c

Question

I'm trying to understand an issue I'm having with an iOS Universal app. I have a UIScrollView which I want the page of to take up the full dimension of the device and adjust itself when rotating.
In my viewDidLoad method, I'm testing with:
NSArray *colors = [NSArray arrayWithObjects:[UIColor orangeColor], [UIColor cyanColor], [UIColor redColor], [UIColor greenColor], [UIColor blueColor], nil];
for (int i = 0; i < colors.count; i++) {
CGRect frame;
frame.origin.x = _scrollView.bounds.size.width * i;
frame.origin.y = 0;
frame.size = _scrollView.bounds.size;
UIView *subview = [[UIView alloc] initWithFrame:frame];
subview.backgroundColor = [colors objectAtIndex:i];
[_scrollView addSubview:subview];
}
_scrollView.contentSize = CGSizeMake(_scrollView.bounds.size.width * colors.count, _scrollView.bounds.size.height);
then I added in the didRotateFromInterfaceOrientation method:
_scrollView.contentSize = CGSizeMake(_scrollView.bounds.size.width * colors.count, _scrollView.bounds.size.height);
for (int i= 0; i< colors.count; i++)
{
CGRect frame;
frame.origin.x = _scrollView.bounds.size.width * i;
frame.origin.y = 0;
frame.size = _scrollView.bounds.size;
UIView *subview= [[_scrollView subviews] objectAtIndex:i];
subview.frame= frame;
}
This seems to work, but I seem to have some clipping on the main view while the device is rotating.
Here's a screenshot of what happens when rotating:
I thought this happened because I changed the size after it was rotated, but I tried to handle it in the willRotateToInterfaceOrientation method, but it gave the wrong result...
Am I handling this incorrectly?
What would be the correct approach?
TIA!
S.
Am I handling this incorrectly?

Answer 1

You should put the code that changes the bounds in willRotateToInterfaceOrientation, but do so in an animation block (using [UIView animateWithDuration:0.4 animations:...])_so that the transition will be smooth rather than immediate.
An extra note is that inside willRotateToInterfaceOrientation, the parent view will not yet have been resized, so you cannot depend on it's bounds to calculate the final position of the views, rather you must do so manually.