OK, answer is no, there is no way to do this without subclassing UICollectionViewFlowLayout.
However, subclassing it is incredibly easy for anyone who is reading this in the future.
First I set up the subclass call MyCollectionViewFlowLayout
and then in interface builder I changed the collection view layout to Custom and selected my flow layout subclass.
Because you’re doing it this way you can’t specify items sizes, etc… in IB so in MyCollectionViewFlowLayout.m I have this…
- (void)awakeFromNib
{
self.itemSize = CGSizeMake(75.0, 75.0);
self.minimumInteritemSpacing = 10.0;
self.minimumLineSpacing = 10.0;
self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
self.sectionInset = UIEdgeInsetsMake(10.0, 10.0, 10.0, 10.0);
}
This sets up all the sizes for me and the scroll direction.
Then …
- (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity
{
CGFloat offsetAdjustment = MAXFLOAT;
CGFloat horizontalOffset = proposedContentOffset.x + 5;
CGRect targetRect = CGRectMake(proposedContentOffset.x, 0, self.collectionView.bounds.size.width, self.collectionView.bounds.size.height);
NSArray *array = [super layoutAttributesForElementsInRect:targetRect];
for (UICollectionViewLayoutAttributes *layoutAttributes in array) {
CGFloat itemOffset = layoutAttributes.frame.origin.x;
if (ABS(itemOffset - horizontalOffset) < ABS(offsetAdjustment)) {
offsetAdjustment = itemOffset - horizontalOffset;
}
}
return CGPointMake(proposedContentOffset.x + offsetAdjustment, proposedContentOffset.y);
}
This ensures that the scrolling ends with a margin of 5.0 on the left hand edge.
That’s all I needed to do. I didn’t need to set the flow layout in code at all.