UICollectionView: minimumInteritemSpacing change on cell selection - ios

Question

In my collection view I want to scale the collection view cell that is selected. Along with that I also want to maintain same interItemSpacing between cells before the selection and after the selection, including enlarged cell. But if I just scale the cell by setting cell.transform property scaled cell overlaps on the neighbor cell.Other cells should adjust themselves to maintain the space. How do I solve this ?
i.e,
cell -50pix- cell -50pix- cell
cell -50pix- scaled cell -50pix- cell

Answer 1

By applying a transform, you are just scaling the view up in size. To adjust the size and allow the rest of the UICollectionView to adjust you will need to return a new size in sizeForItemAtIndexPath:
When the item is selected, you should reload that item at that indexPath using:
[collectionView reloadItemAtIndexPath:selectedIndexPath]
Replace selectedIndexPath with name of your variable storing the selected indexPath.
You don't want to invalidateLayout because you're just changing the appearance of one item.

Answer 2

I don't know whether this is the best solution,
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
CollectionViewCell *cell = (CollectionViewCell*)[collectionView dequeueReusableCellWithReuseIdentifier:#"cell" forIndexPath:indexPath];
cell.backgroundColor = [UIColor redColor];
return cell;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{
if ([indexPath isEqual:selectedIndexPath]) {
return CGSizeMake(175, 175); // return enlarged size if selected cell
}
return CGSizeMake(150, 150);
}
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
selectedIndexPath = indexPath; // set selected indexPath
[collectionView performBatchUpdates:^{
[collectionView.collectionViewLayout invalidateLayout];
} completion:^(BOOL finished) {
}];
}
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{
return UIEdgeInsetsMake(0, 0,0, 0);
}
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{
return 20;
}
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{
return 20;
}