UIScrollView setContentOffset: animated: not working - iphone

Question

I have a problem with two infinite UIScrollViews which do not change their offsets properly.
An item in the first UIScrollView corresponds with another one in the second. Then, I want to put the clicked item in the second place and animate the change in both UIScrollView. To get this done properly, I use this two methods:
When item is clicked:
- (void)click:(id)sender {
NSInteger index = [[self cells] indexOfObject:sender];
if (index == 1)
{
CategoriesViewController *viewController = [[CategoriesViewController alloc] initWithNibName:#"CategoriesView" bundle:nil];
[[viewController tit] setText:NSLocalizedString([[self categories] objectAtIndex:1], nil)];
[[self navigationController] pushViewController:viewController animated:YES];
}
else
{
for (NSInteger i = 0; i < index - 1; i++)
{
NSObject *object = [[self categories] objectAtIndex:0];
[[self categories] removeObjectAtIndex:0];
[[self categories] addObject:object];
}
for (NSInteger i = 0; i < index - 1; i++)
{
CollectionCellViewController *cell = [[self cells] objectAtIndex:0];
[[self cells] removeObjectAtIndex:0];
[[self cells] addObject:cell];
}
for (NSInteger i = 0; i < index - 1; i++)
{
UIImageView *image = [[self images] objectAtIndex:0];
[[self images] removeObjectAtIndex:0];
[[self images] addObject:image];
}
[self updateViewsOffsets];
}
}
- (void)updateViewsOffsets {
NSInteger y = 0;
for (NSInteger i = 0; i < [[self cells] count]; i++)
{
CollectionCellViewController *cell = [[self cells] objectAtIndex:i];
[[cell view] setTag:i];
if (i == 1)
{
[cell setSelected:[[self categories] objectAtIndex:i]];
}
else
{
[cell setDeselected:[[self categories] objectAtIndex:i]];
}
CGRect rect = [[cell view] frame];
rect.origin.x = 0.0f;
rect.origin.y = y;
[[cell view] setFrame:rect];
y += [[self table] frame].size.height / 2.0f;
}
y = 0;
for (NSInteger i = 0; i < [[self images] count]; i++)
{
UIImageView *image = [[self images] objectAtIndex:i];
CGRect rect = [image frame];
rect.origin.x = 0.0f;
rect.origin.y = y;
[image setFrame:rect];
y += [[self gallery] frame].size.height;
}
[[self table] setContentOffset:CGPointMake(0.0f, [[self table] frame].size.height / 2.0f) animated:YES];
[[self gallery] setContentOffset:CGPointMake(0.0f, [[self table] contentOffset].y * 8.0f) animated:YES];
}
The change is made, but without animation, it have the same behaviour with YES or NO, it only calls scrollViewDidScroll: once. However, I use setContentOffset: animated: in other methods where it works properly with both UIScrollView.
Any idea, please. Thank you very much in advance.

Answer 1

I just had this issue. I fixed it by dispatching the call to the main thread. Try this:
dispatch_async(dispatch_get_main_queue(), ^{
[[self table] setContentOffset:CGPointMake(0.0f, [[self table] frame].size.height / 2.0f) animated:YES];
[[self gallery] setContentOffset:CGPointMake(0.0f, [[self table] contentOffset].y * 8.0f) animated:YES];
});