UIScrollView + change orientation = messed up subviews (iPad) - ios

Question

I want to use a UIScrollView as my main container in the app, enabling me to swipe back and forth between subviews. To achieve this, I created a UIViewController subclass with a UIScrollView IBOutlet:
In the viewDidLoad method I construct the sub-pages:
for (int i= 0; i< pageCount; i++)
{
CGRect frame = self.scrollView.frame;
frame.origin.x = frame.size.width * i;
frame.origin.y = 0;
UIWebView* aWebView= [[UIWebView alloc] initWithFrame:frame];
[self.scrollView addSubview:aWebView];
}
When launching the app (portrait mode), everything works. That is, the UIWebViews are layed out side by side with the correct dimensions, and I can swipe back and forth between them.
When I rotate to landscape, it seems that neither the scrollview size nor the subviews are resized.
I don't know what I should do in order to resize the subviews and the scrollview itself, or at what point in code I should do anything, and I cant seem to find any examples for this.
Anyone know what to do?
[edit] Attempt to adjust sizes as suggested by mahboudz:
- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width * pageCount, self.scrollView.frame.size.height);
for (int i= 0; i< pageCount; i++)
{
CGRect frame = self.scrollView.frame;
frame.origin.x = frame.size.width * i;
frame.origin.y = 0;
UIWebView* view= [[self.scrollView subviews] objectAtIndex:i];
view.frame= frame;
}
}
This kind of does what I want, but has the following issues:
1) one can see the subviews grow to correct screen size upon changing orientation
2) when the current page is, for example, page 2 of 5 pages, the page is not fully visible after orientation was changed, but is off-screen by like 40 pixels
3) I get strange effects depending on whether the app is launched in portrait or landscape mode (simulator), ill try to explain:
When the app is launched in portrait mode:
The shape/border of the subviews looks messed up/offscreen, see screenshots:
http://i53.tinypic.com/21jr76x.png
when I rotate to landscape, everything looks okay, scrolling works superb. even when I rotate back to portrait, everything is great now:
http://i55.tinypic.com/if3iiw.png
When the app is launchend in landscape mode:
I get the same messed up/offscreen glitches as in portrait mode
Switching back and forth between portrait and landscape fixes this for landscape mode
BUT: Portrait mode will have the subviews with the width of the landscape mode, thus subviews are too wide
I tried to fix 1) doing the code above in willRotateToInterfaceOrientation however it completely messed up the layout.
I fixed 2) by adding the following code to didRotateFromInterfaceOrientation:
// update the scroll view to the appropriate page
CGRect frame = self.scrollView.frame;
frame.origin.x = frame.size.width * self.currentPage;
frame.origin.y = 0;
[self.scrollView scrollRectToVisible:frame animated:NO];
Note: current page is determined in scrollViewDidScroll
I dont have any idea how to fix 3)

Answer 1

You would need to reset the frame size, content size and the content offset in order to get the subviews in a proper position.
CGFloat screenHeight =[UIScreen mainScreen].bounds.size.height;
CGFloat screenWidth =[UIScreen mainScreen].bounds.size.width;
self.scrollView.frame = CGRectMake(0, 0, screenWidth, screenHeight);
self.scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * numberOfPages, self.scrollView.frame.size.height);
self.scrollView.contentOffset = CGPointMake(visiblePageBeforeRotation * self.scrollView.bounds.size.width, 0);
This code should be placed in the method
-(void)willRotateToInterfaceOrientation: (UIInterfaceOrientation)orientation duration:(NSTimeInterval)duration
Check as well the answer on this question:
Clean autorotation transitions in a paging UIScrollView
It has good example named Rotolling for rotating UIScrollView with paging enabled.
Hope this helps.
P.S: I am facing a problem on repositioning the center of the UIWebView on the rotation.

Answer 2

You need to implement viewWillRotate/viewDidRotate and make adjustments to our content size and orientation as needed.