How to display 3 cells per row in UICollectionView

问题:

I used a custom flow layout according to this post. Here is my implementation:

@implementation CustomLayout
-(void)prepareLayout{
[super prepareLayout];
//    [self invalidateLayout];
if(self.collectionView){
    CGSize newItemSize=self.itemSize;

// Number of items per row
    int itemsPerRow=3;

    float totalSpacing=self.minimumLineSpacing*(itemsPerRow-1);

    newItemSize.width=(self.collectionView.bounds.size.width -totalSpacing)/itemsPerRow;

    if(self.itemSize.height>0){
        float itemAspectRatio=self.itemSize.width/self.itemSize.height;
        newItemSize.height=newItemSize.width/itemAspectRatio;
    }

    [self setItemSize:newItemSize];

}


}
@end

This is what I've got: What did I miss? I've come across some other SO posts but no luck so far.

回答1:

Swift 3.0. Works for both horizontal and vertical scroll directions and variable spacing

Declare number of cells you want per row

let numberOfCellsPerRow: CGFloat = 3

Configure flowLayout to render specified numberOfCellsPerRow

if let flowLayout = collectionView?.collectionViewLayout as? UICollectionViewFlowLayout {
    let horizontalSpacing = flowLayout.scrollDirection == .vertical ? flowLayout.minimumInteritemSpacing : flowLayout.minimumLineSpacing
    let cellWidth = (view.frame.width - max(0, numberOfCellsPerRow - 1)*horizontalSpacing)/numberOfCellsPerRow
    flowLayout.itemSize = CGSize(width: cellWidth, height: cellWidth)
}

回答2:

//Make use of UICollectionViewDelegateFlowLayout Protocol

class RVC: UICollectionViewController {
//some code
}

extension RVC: UICollectionViewDelegateFlowLayout{

    func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
    {
          var collectionViewSize = collectionView.frame.size
          collectionViewSize.width = collectionViewSize.width/3.0 //Display Three elements in a row.
          collectionViewSize.height = collectionViewSize.height/4.0
          return collectionViewSize
    }

For more information go through below link.

UICollectionView Set number of columns

回答3:

itemSpacing = "Spacing size between cell."

itemsInOneLine = "Number of item which you want to display in single row."

collectionWidth = "Width of your collection view"

let layout:UICollectionViewFlowLayout =  UICollectionViewFlowLayout()   
let width = (collectionWidth) - itemSpacing * CGFloat(itemsInOneLine - 1)
layout.itemSize = CGSize(width:floor(width/CGFloat(itemsInOneLine)),height:width/CGFloat(itemsInOneLine))

回答4:

You don't have to do it by coding. You just have to do in xib.as per iPhone 5 or 5s width become 320. and you want to show 3 cells per row so u have to do 320/3 and as per you get whatever answer your cell size is as per result.If any doubt of my answer ask me.