UICollectionViewCell dynamic height with autolayout

Question

I am using auto layout with UICollectionViewCell. So the idea is to allow CollectionViewCell to determine it's size based on layouts. All the constraints are set properly but the problem is that I can not calculate it's size for data source method

collectionView:layout:sizeForItemAtIndexPath:

Ideally I would like to calculate Cell's height doing the following:

static MyCell *myCell = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
    myCell = [[MyCell alloc] initWithFrame:CGRectZero];
});
cell.model = model;
[cell updateConstraints];
[cell layoutSubviews];
return cell.frame.size;

but it doesn't force constraints to update, so the cell's frame is zero. Can you advice me how can I calculate cell's size based on it's constraints?

Thanks

did you find any solution for this problem; i faced the same problem — Sonic, Jun 16 '15 at 23:58

Mihawk · Answer 1 · 2015-07-24T07:20:56.817

here is the solution

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    YourCollectionCell * cell = (YourCollectionCell *) [YourCollectionViewObj cellForItemAtIndexPath:indexPath];

            if (cell == nil) {

                NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"YourCollectionCell" owner:self options:nil];
                cell = [topLevelObjects objectAtIndex:0];
                cell.frame = CGRectMake(0, 0, CGRectGetWidth(self.view.frame), 20);
                // SET YOUR CONTENT
                [cell layoutIfNeeded];

            }

            CGSize CellSize = [cell systemLayoutSizeFittingSize:UILayoutFittingCompressedSize withHorizontalFittingPriority:UILayoutPriorityDefaultHigh verticalFittingPriority:UILayoutPriorityDefaultLow];


            return CellSize;
 }

I'm doing this in swift, but nevertheless I cannot load the collection cell from the nib, as the loadNibNamed cannot find my cell identifier. — xtrinch, May 04 '16 at 13:02

score 0 · Answer 2 · answered Jul 16 '15 at 15:58

0

I think you should return this size:

return [cell systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];

answered Jul 16 '15 at 15:58

jano

49
5

score 0 · Answer 3 · answered Jul 06 '16 at 21:26

For your dynamic height of the UICollectionViewCell in UIcollectionViewcontroller , you need to implement below method: -

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

UICollectionViewCell dynamic height with autolayout

3 Answers3

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