uicollectionview variable cell height

Question

I have a UICollectionView with a reusable header (that's why I'm using collection and not tableview). The cell needs to have a variable height, depending on a UILabel. I know in UITableView you can use UITableViewAutomaticDimension to auto resize the cell, but I can't find an analogous function for UICollectionView. Any idea? I suppose I should start with sizeForItemAtIndexPath ?

 override func collectionView(collectionView: UICollectionView,
    layout collectionViewLayout: UICollectionViewLayout,
    sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {

        let height = // needs to be variable
        let width = UIScreen.mainScreen().bounds.width

        return CGSize(width: width, height: height)


}

Answer 1

Setup the cell with auto layout constraints then set the estimatedItemSize property of the your UICollectionView's UICollectionViewFlowLayout. For example:

self.collectionView.collectionViewLayout.estimatedItemSize = CGSize(100,100)