以前的版本并没有真正工作的部分> 1。所以我的解决方案在这里找到了https://codentrick.com/create-a-tag-flow-layout-with-uicollectionview/。对于懒惰的人:

override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
    let attributesForElementsInRect = super.layoutAttributesForElements(in: rect)
    var newAttributesForElementsInRect = [UICollectionViewLayoutAttributes]()
    // use a value to keep track of left margin
    var leftMargin: CGFloat = 0.0;
    for attributes in attributesForElementsInRect! {
        let refAttributes = attributes 
        // assign value if next row
        if (refAttributes.frame.origin.x == self.sectionInset.left) {
            leftMargin = self.sectionInset.left
        } else {
            // set x position of attributes to current margin
            var newLeftAlignedFrame = refAttributes.frame
            newLeftAlignedFrame.origin.x = leftMargin
            refAttributes.frame = newLeftAlignedFrame
        }
        // calculate new value for current margin
        leftMargin += refAttributes.frame.size.width + 10
        newAttributesForElementsInRect.append(refAttributes)
    }

    return newAttributesForElementsInRect
}

我使用monotouch，所以名称和代码会有点不同，但你可以通过确保集合视图的宽度等于(x *单元格宽度)+ (x-1) * MinimumSpacing与x =每行单元格的数量来做到这一点。

只需要根据MinimumInteritemSpacing和Cell的宽度执行以下步骤

1)我们根据单元格大小+当前插入+最小间距计算每行项目的数量

float currentTotalWidth = CollectionView.Frame.Width - Layout.SectionInset.Left - Layout.SectionInset.Right (Layout = flowlayout)
int amountOfCellsPerRow = (currentTotalWidth + MinimumSpacing) / (cell width + MinimumSpacing)

2)现在你有了所有信息来计算集合视图的预期宽度

float totalWidth =(amountOfCellsPerRow * cell width) + (amountOfCellsPerRow-1) * MinimumSpacing

3)所以当前宽度与预期宽度之差为

float difference = currentTotalWidth - totalWidth;

4)现在调整insets(在本例中，我们将其添加到右侧，因此集合视图的左侧位置保持不变

Layout.SectionInset.Right = Layout.SectionInset.Right + difference;

故事板的方法

在你的故事板中选择CollectionView，然后进入尺寸检查器，设置单元格和行的最小间距为5

Swift 5编程方式

lazy var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .horizontal

        //Provide Width and Height According to your need
        let width = UIScreen.main.bounds.width / 4
        let height = UIScreen.main.bounds.height / 10
        layout.itemSize = CGSize(width: width, height: height)

        //For Adjusting the cells spacing
        layout.minimumInteritemSpacing = 5
        layout.minimumLineSpacing = 5

        return UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
    }()

我偶然发现了与op类似的问题。不幸的是，接受的答案不适合我，因为collectionView的内容不会正确居中。因此，我提出了一个不同的解决方案，只需要在collectionView中的所有项目都具有相同的宽度，这似乎是问题中的情况:

#define cellSize 90

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
    float width = collectionView.frame.size.width;
    float spacing = [self collectionView:collectionView layout:collectionViewLayout minimumInteritemSpacingForSectionAtIndex:section];
    int numberOfCells = (width + spacing) / (cellSize + spacing);
    int inset = (width + spacing - numberOfCells * (cellSize + spacing) ) / 2;

    return UIEdgeInsetsMake(0, inset, 0, inset);
}

该代码将确保…minimumInteritemSpacing…将是每个collectionViewCell之间的精确间距，并进一步保证所有的单元格一起将在collectionView

Swift 5 UIKit编程

 //Create UICollectionView
lazy var collectionView: UICollectionView = {
    
    let layout = UICollectionViewFlowLayout()
    layout.scrollDirection = .horizontal
    
    //CollectionCellView width autoSize
    layout.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
    
    let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
    collectionView.translatesAutoresizingMaskIntoConstraints = false
    
    collectionView.register(CustomCollectionViewCell.self, forCellWithReuseIdentifier: cellId)
    collectionView.backgroundColor = .clear
    collectionView.delegate = self
    collectionView.dataSource = self
    collectionView.alwaysBounceHorizontal = true

//Add Spacing in each cell
    layout.minimumInteritemSpacing = 15
    layout.minimumLineSpacing = 15
    
    return collectionView
}()

我尝试了iago849的答案，它起作用了。

斯威夫特4

open override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
    guard let answer = super.layoutAttributesForElements(in: rect) else {
        return nil
    }
    let count = answer.count
    for i in 1..<count {
        let currentLayoutAttributes = answer[i]
        let prevLayoutAttributes = answer[i-1]
        let origin = prevLayoutAttributes.frame.maxX
        if (origin + CGFloat(spacing) + currentLayoutAttributes.frame.size.width) < self.collectionViewContentSize.width && currentLayoutAttributes.frame.origin.x > prevLayoutAttributes.frame.origin.x {
            var frame = currentLayoutAttributes.frame
            frame.origin.x = origin + CGFloat(spacing)
            currentLayoutAttributes.frame = frame
        }
    }
    return answer
}

这是github项目的链接。 https://github.com/vishalwaka/MultiTags