迅速uicollectionview单元格之间没有空间，只有单元格之间的屏幕

Question

In my collectionview I have two layouts, one list and one grid (two colum).

When I have list activated there is a 2px space between the cell and the screen on each side.

But when I change to grid layout I only get a small space between my cells and not the cells and the screen. I would like to add a 2px space between the cell and the screen.

Code for two colum grid:

class GridLayout: UICollectionViewFlowLayout {

    var numberOfColumns: Int = 3

    init(numberOfColumns: Int) {
        super.init()
        minimumLineSpacing = 1
        minimumInteritemSpacing = 1

        self.numberOfColumns = numberOfColumns
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override var itemSize: CGSize {
        get {
            if let collectionView = collectionView {
                let itemWidth: CGFloat = (collectionView.frame.width/CGFloat(self.numberOfColumns)) - self.minimumInteritemSpacing
                let itemHeight: CGFloat = 260.0
                return CGSize(width: itemWidth, height: itemHeight)
            }

            // Default fallback
            return CGSize(width: 100, height: 100)
        }
        set {
            super.itemSize = newValue
        }
    }

    override func targetContentOffset(forProposedContentOffset proposedContentOffset: CGPoint) -> CGPoint {
        return proposedContentOffset
    }

}

And code for list which works:

class ListLayout: UICollectionViewFlowLayout {

    var itemHeight: CGFloat = 180

    init(itemHeight: CGFloat) {
        super.init()
        minimumLineSpacing = 1
        minimumInteritemSpacing = 1
        self.itemHeight = itemHeight
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override var itemSize: CGSize {
        get {
            if let collectionView = collectionView {
                //Adding -4 to set a 2px space between cell and screen
                let itemWidth: CGFloat = collectionView.frame.width - 4
                return CGSize(width: itemWidth, height: self.itemHeight)
            }

            // Default fallback
            return CGSize(width: 100, height: 100)
        }
        set {
            super.itemSize = newValue
        }
    }

    override func targetContentOffset(forProposedContentOffset proposedContentOffset: CGPoint) -> CGPoint {
        return proposedContentOffset
    }

}

Answer 1

Change your init of UICollectionViewFlowLayout to this:-

init(numberOfColumns: Int) {
    super.init()
    minimumLineSpacing = 1
    minimumInteritemSpacing = 1
    self.numberOfColumns = numberOfColumns

    let leftPadding: CGFloat = 2.0
    let rightPadding: CGFloat = 2.0
    sectionInset = UIEdgeInsetsMake(0, leftPadding, 0, rightPadding)
}

And change your itemSize getter method to this:-

get {
        if let collectionView = collectionView {
           let padding: CGFloat = 2.0
           let itemWidth: CGFloat = (collectionView.frame.width/CGFloat(self.numberOfColumns)) - (self.minimumInteritemSpacing+ 2*padding)
           let itemHeight: CGFloat = 260.0
           return CGSize(width: itemWidth, height: itemHeight)
        }

        // Default fallback
        return CGSize(width: 100, height: 100)
}

Answer 2

Below is how you set custom cell spacing in a collectionview. You have to create an extension.

extension ViewController : UICollectionViewDelegateFlowLayout {

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

    return //whatever you want in CGSize(width:, height:)//
           //so if you want 2px before screen, between cells, and after cell, you would put (self.view.bounds.width - 6) / 2 for width

}

Make sure the "ViewController" that follows extension is the name of your viewcontroller.

Answer 3

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAtIndex section: Int) -> UIEdgeInsets { return UIEdgeInsetsMake(2,2,2,2) }

  - (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
      return UIEdgeInsetsMake(2,2,2,2);
  } this code may help u.