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
A layout object that organizes items into a grid with optional header and footer views for each section.
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;
}
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