Dismiss modal view changes underlying UIScrollView

Question

There must be something basic that I am missing here. I have a UIScrollView open, which is controlled by a customer UIScrollViewController (called DataController). At a certain point in time, input from the user is needed, so I open a modal UIViewController from the DataController:

ElementSelectController *viewController = [[ElementSelectController alloc] initWithNibName:@"ElementSelectController" bundle:nil];
viewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
viewController.theDelegate = self;
[self presentModalViewController:viewController animated:YES];

Once the user is ready with the modal view, it is dismissed again. This also happens from the DataController:

[self dismissModalViewControllerAnimated:YES];

This all works fine. But when the modal view is gone, it turns out that the underlying UIScrollView is resized to full screen, and scrolled to position (0,0). This is the case even with a simple modal view that does not do anything else but be dismissed. Obviously, I want the UIScrollView to remain in the same state and size as it was before the modal view came up.

Any ideas what I am doing wrong?

I checked the stack trace when the UIScrollView frame is set (through a break-point in setFrame: of a custom UIScrollView), and it appears that it is called from:

-[UITransitionView transition:fromView:toView:]

which is called via, via from the dismissModalViewControllerAnimated call.

I don't know why that's happening, but you could always store the UIScrollView contentOffset and reset if after the modal disappears. — NWCoder
Thanks. That is what I do now as a work-around. I save the frame and the contentOffset of the UIScrollView, and reset them immediately after the dismiss call. That seems to work, but it feels like a hack. I would sure like to know what the normal way to handle this is. — fishinear
@Smriti Yadav I have no custom code in viewWillAppear, neither in the DataController, nor in the modal view. The model view is right now just a UIView with a navigation bar and a Cancel button, built in Interface Builder. No custom code at all there. — fishinear

EricLeaf EricLeaf · Accepted Answer · 2011-09-21T05:51:02

-[UITransitionView transition:fromView:toView:]

Is perfectly normal for transitioning from the modal back to your view. This is the animation etc, try you modal with animation if you think that could make a difference.

Take a look at your viewWillAppear, WillDisappear, DidAppear... Even the Load and Unload if appropriate, although unlikely those are called for your trivial test with nothing in the modal. Try placing some logging in those methods to see which is called.

Also are you saying there is no custom code in those methods, or your controller doesn't override them at all? Could make a difference.

Dismiss modal view changes underlying UIScrollView

1 Answers