自定义layout布局搜索热词 swift版

之前写过OC版本的标签布局，在自定义标签布局中可以查看，下面介绍swift版本的标签布局

和OC版一样，同样是自定义layout布局方式，主要代码如下：

override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        let attrs = UICollectionViewLayoutAttributes(forCellWith: indexPath)
        let width = layoutDelegate?.itemWidth(layout: self, indexpath: indexPath)
        let height = layoutDelegate?.itemHeight(layout: self, indexpath: indexPath)
        var x:CGFloat = 0
        var y:CGFloat = 0
        var leftMargin:CGFloat = 0
        var rowMargin:CGFloat = 0
        var columnMargin:CGFloat = 0
        if let delegate = layoutDelegate {
            if delegate.responds(to: #selector(YGLayoutDelegate.itemEdgeInset(layout:))) {
                leftMargin = delegate.itemEdgeInset!(layout: self).left
            }else {
                leftMargin = defaultEdgeInset.left
            }
            
            if delegate.responds(to: #selector(YGLayoutDelegate.itemRowMargin(layout:))) {
                rowMargin = delegate.itemRowMargin!(layout: self)
            }else {
                rowMargin = defaultRowMargin
            }
            
            if delegate.responds(to: #selector(YGLayoutDelegate.itemColumnMargin(layout:))) {
                columnMargin = delegate.itemColumnMargin!(layout: self)
            }else {
                columnMargin = defaultCoumnMargin
            }
        }
        
        if maxX + width! + leftMargin > (collectionView?.frame.size.width)! {
            maxX = leftMargin
            x = maxX
            maxY = rowMargin + maxY + height!
            y = maxY
            maxX = maxX + width! + columnMargin
        }else {
        
            x = maxX
            y = maxY
            maxX = maxX + width! + columnMargin
        }
        attrs.frame = CGRect(x: x, y: y, width: width!, height: height!)
        var newFrame = collectionView?.frame
        newFrame?.size.height = maxY + height! + rowMargin
        collectionView?.frame = newFrame!
        return attrs
    }

代理方法的定义如下：

 @objc protocol YGLayoutDelegate:NSObjectProtocol {
    
    func itemWidth(layout:YGLayout,indexpath:IndexPath) -> CGFloat
    
    func itemHeight(layout:YGLayout,indexpath:IndexPath) -> CGFloat

    @objc optional func itemRowMargin(layout:YGLayout) -> CGFloat
    
    @objc optional func itemColumnMargin(layout:YGLayout) -> CGFloat
    
    @objc optional func itemEdgeInset(layout:YGLayout) -> UIEdgeInsets
    
}

外界调用只需要完成下面的方法：

    func itemWidth(layout: YGLayout, indexpath: IndexPath) -> CGFloat {
        let model = dataSource[indexpath.item]
        return model.getItemSize().width
    }
    
    func itemHeight(layout: YGLayout, indexpath: IndexPath) -> CGFloat {
        let model = dataSource[indexpath.item]
        return model.getItemSize().height
    }
    
    func itemRowMargin(layout: YGLayout) -> CGFloat {
        return scaleToWidth(size: 20)
    }
    
    func itemColumnMargin(layout: YGLayout) -> CGFloat {
        return scaleToHeight(size: 20)
    }

具体源码可以到我的github上查看