CODEWITHSUNDEEP
iosswiftuicollectionviewuicollectionviewcelluicollectionviewlayout
Jacob Cavin
Jacob Cavin

Reputation: 2319

Call a UICollectionView Cell in sizeForItemAtIndexPath

I want to be able to call my UICollectionViewCell class in the sizeForItemAtIndexPath function. Like this:

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

    let cell = MyCollectionViewCell()

    let itemHeights = cell.titleLabel.frame.size.height + cell.subtitleLabel.frame.size.height + 20 

    return CGSize(width: self.view.frame.size.width - 30, height: itemHeights + cell.thumbnail.frame.size.height)

}

The problem is that cell.titleLabel.frame.size.height, cell.subtitleLabel.frame.size.height, and cell.thumbnail.frame.size.height are all returning nil. I assume this is because whenever sizeForItemAtIndexPath is called, the cell has not loaded yet and cellForItemAtIndexPath has not been called, yet.

I need to know this because the cell.titleLabel can be multiple lines and widths which are set in the cellForItemAtIndexPath.

Any idea?

Upvotes: 4

Views: 3327

Answers (1)

PGDev
PGDev

Reputation: 24341

sizeForItemAt is called before your cell is actually created and configured with the required data. That is the reason you don't get correct data that you need.

Try this:

Create a dummy cell in sizeForItemAt by dequeuing it from the collectionView. Configure the cell with actual data that you want to display. After configuring it get what data you need, i.e.

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
{
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
    //Configure your cell with actual data
    cell.contentView.layoutIfNeeded()
    //Calculate the size and return
}

Upvotes: 2

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