There was a requirement where I was setting custom size for UICollectionViewCell. Custom size wasn’t dynamic but a static tall portrait ratio size. The effective way to set your own custom size is to call implement delegate method of protocol UICollectionViewDelegateFlowLayout:

func collectionView_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return estimatedCollectionSize
}

The problem:

UICollectionView was calculating its cell’s size automatically to for the content and just plainly ignoring the implementation of delegate function.

I checked storyboard inspector and found out that estimate size property of UICollectionView was set to automatic. My solution was to set it to none.

Image solution:

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