UICollectionViewCell expand/collapse with intrinsic size

Question

I have a collection view with a custom flow layout, and many different cells of different height. The width of the collection view changes on device rotation, so the width o

Answer 1

Follow these steps:

1). Create a boolean variable named isExpanded to manage expand / collapse

2.) Add a target and action to the show more button

[yourCellName.btnShowMore addTarget:self action:@selector(ShowMoreButtonClicked) forControlEvents:UIControlEventTouchUpInside];

3.) In sizeForItemAtIndexPath for managing height, add:

 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{

if (isExpanded && indexPath.row == 0) {
        return CGSizeMake(CGRectGetWidth(self.view.frame), calculated height for the expanded cell);
    }
   return CGSizeMake(CGRectGetWidth(self.view.frame), default height);
}

4.) Then in the ShowMoreButtonClicked method

- (void)ShowMoreButtonClicked{
    if (isExpanded) {
       isExpanded = FALSE;
       [collection_viewCus reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForRow:0 inSection:0]]];

    }
    else {
       isExpanded = TRUE;
       [collection_viewCus reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForRow:0 inSection:0]]];
   }}

5.) Add this line in your cellForItemAtIndexPath

 [yourCellName layoutIfNeeded];

6.) Build & run

Answer 2

The previous response is good but if you want some animation you need to do this three steps:

1.Invalidate your collectionViewLayout

self.collectionView.collectionViewLayout.invalidateLayout()

2.Reload desired indexPath or all the data inside a performBatchUpdates block

collectionView.performBatchUpdates({
            self.collectionView.reload(at: DESIRED_INDEXPATH)
        }, completion: nil)

3.Return the new height calculated in sizeForItemAtIndexpath delegate method