如何设置单元格间距和UICollectionView-UICollectionViewFlow

Question

我正在尝试添加UICollectionView到ViewController，我需要“每行”有3个单元格，单元格之间没有空格（它看起来应该像网格）。单元格的宽度应该是屏幕尺寸的三分之一，所以我认为layout.item宽度应该相同。但是然后我得到这个：

layout.itemSize width = screenSize.width / 3

如果我减小该尺寸（例如减少7或8像素），效果会更好，但是行中的第三个单元格不是完全可见的，并且我仍然有该空白（顶部和底部以及左侧和右侧）。

在此处输入图片说明

class ViewController: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource {

    var collectionView: UICollectionView?

    var screenSize: CGRect!

    var screenWidth: CGFloat!

    var screenHeight: CGFloat!

    override func viewDidLoad() {

        super.viewDidLoad()

        screenSize = UIScreen.mainScreen().bounds

        screenWidth = screenSize.width

        screenHeight = screenSize.height

        // Do any additional setup after loading the view, typically from a nib

        let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()

        layout.sectionInset = UIEdgeInsets(top: 20, left: 0, bottom: 10, right: 0)

        layout.itemSize = CGSize(width: screenWidth / 3, height: screenWidth / 3)

        collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)

        collectionView!.dataSource = self

        collectionView!.delegate = self

        collectionView!.registerClass(CollectionViewCell.self, forCellWithReuseIdentifier: "CollectionViewCell")

        collectionView!.backgroundColor = UIColor.greenColor()

        self.view.addSubview(collectionView!)

    }

    func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {

        return 1

    }

Answer 1

添加这2行layout.minimumInteritemSpacing = 0layout.minimumLineSpacing = 0所以你有了：   // Do any additional setup after loading the view, typically from a nib.        let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()        layout.sectionInset = UIEdgeInsets(top: 20, left: 0, bottom: 10, right: 0)        layout.itemSize = CGSize(width: screenWidth/3, height: screenWidth/3)        layout.minimumInteritemSpacing = 0        layout.minimumLineSpacing = 0        collectionView!.collectionViewLayout = layout这将删除所有空格并为您提供网格布局：在此处输入图片说明如果希望第一列的宽度等于屏幕宽度，请添加以下功能：func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {    if indexPath.row == 0    {        return CGSize(width: screenWidth, height: screenWidth/3)    }    return CGSize(width: screenWidth/3, height: screenWidth/3);}网格布局现在看起来像（我还在第一个单元格中添加了蓝色背景）

Answer 2

对于Swift 3和XCode 8来说，这可行。请按照以下步骤来实现：{    let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()    let width = UIScreen.main.bounds.width    layout.sectionInset = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)    layout.itemSize = CGSize(width: width / 2, height: width / 2)    layout.minimumInteritemSpacing = 0    layout.minimumLineSpacing = 0    collectionView!.collectionViewLayout = layout}将此代码放入viewDidLoad（）函数。

Answer 3

在某些情况下，设置UICollectionViewFlowLayoutin viewDidLoad或ViewWillAppear不影响collectionView。设置UICollectionViewFlowLayoutin viewDidAppear可能会导致在运行时看到像元大小的变化。Swift 3中的另一个解决方案：extension YourViewController : UICollectionViewDelegateFlowLayout{    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {        return UIEdgeInsets(top: 20, left: 0, bottom: 10, right: 0)    }    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {        let collectionViewWidth = collectionView.bounds.width        return CGSize(width: collectionViewWidth/3, height: collectionViewWidth/3)    }    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {        return 0    }    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {        return 20    }}