How to show three columns in a CollectionView using swift4 in all devices

问题

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


    if collectionView == self.collectionViewVideo {

        var collectionViewSize = collectionViewVideo.frame.size
        collectionViewSize.width = collectionViewSize.width/3.0 //Display Three elements in a row.
        return collectionViewSize
    } else {
        return CGSize(width: 60, height: 60)
    }


}

回答1:

You also need to take space in account. Space is your collection view item space

Following is the code has two cells and 20 spaces. (I am not writing exactly code you need You should do it by your self)

extension YourViewController : UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 20
    }

    //--------------------------------------------------------------------------------

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return 20;
    }

    //--------------------------------------------------------------------------------

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: ( self.collectionView.frame.size.width - 60 ) / 2,height:( self.collectionView.frame.size.width - 60 ) / 2)
    }

    //--------------------------------------------------------------------------------

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
       return UIEdgeInsetsMake(0, 20, 20, 20)
    }
}

Here 60 means SPACE 20 CELL SPACE 20 CELL SPACE 20

来源：https://stackoverflow.com/questions/49795872/how-to-show-three-columns-in-a-collectionview-using-swift4-in-all-devices