UICollectionView autosize height

Question

How do I properly resize a UICollectionView so that it fully displays its contents? I have tried many things, including setting its frame, calling reloadData an

Answer 1

For me it is even simpler I think

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath

{
//add following code line after adding cells, before Return
...........
.........
scrollView.contentSize = = collectionView.contentSize;

//now scrollView size is equal to collectionView size. No matter how small or big it is.

return cell;
}

Answer 2

I solved this eventually by fixing all Auto Layout issues, fixing the height of the collection view using a constraint. Then, whenever I know the content has changed I update the value of the constraint using the value collectionView.contentSize.height:

self.verticalLayoutConstraint.constant = self.collectionView.contentSize.height;

Then the collection view is resized properly and it behaves nicely within the overall scrollview. I have updated the GitHub test project with my changes.

To me, doing this by updating the constraint manually instead of being able to tell iOS: "make the frame height of the collection view as large as needed" does not feel right to me, but it's the best I have come up with so far. Please post a better answer if you have one.

Answer 3

The simplest method I found is to override sizeThatFits: methods as is:

- (CGSize)sizeThatFits:(CGSize)size
{
    if( self.superview )
        [self.superview layoutIfNeeded]; // to force evaluate the real layout

    return self.collectionViewLayout.collectionViewContentSize;
}