iOS swift 标签选择器 支持居中对齐，左对齐,右对齐

文章掘金地址：https://juejin.cn/post/7070728070151274532 文章简书地址：https://www.jianshu.com/p/41600e45a10a

基本效果图 圆角效果图 自定义cell

实现方法

UICollectionView 重新自定义 UICollectionViewLayout

demo 地址 https://gitee.com/Sunny0123/lztag(不更新，最新到github) 最新代码地址：https://github.com/lizhi0123/LZTag

v1.0.1 支持 swift5 v1.0.0 支持 swift 4.2

• 引用

更新pod命令

pod repo update

podfile 文件里添加

pod 'LZTag'

命令安装

pod install

• LZTagLayout 方法属性说明

方法/属性	说明
func tagLayout(_ layout: LZTagLayout, collectionView: UICollectionView, textForItemAt indexPath: IndexPath) -> String	delegate 方法 文字内容for cell ；textForItemAt + itemFont + tagInnerMarginForItemAt 共同控制cell的宽度
func tagLayout(_ layout: LZTagLayout, collectionView: UICollectionView, sizeForSupplementaryElementOfKind kind: String, at section: Int) -> CGSize	section head footer size
func tagLayout(_ layout: LZTagLayout, collectionView: UICollectionView, tagInnerMarginForItemAt indexPath: IndexPath) -> CGFloat	标签的内边距; textForItemAt + itemFont + tagInnerMarginForItemAt 共同控制cell的宽度
itemSpacing	元素间距
lineSpacing	行间距
itemHeight	标签的高度
itemFont	标签的字体 ; textForItemAt + itemFont + tagInnerMarginForItemAt 共同控制cell的宽度
delegate	代理
✅contentAlignment	对其方式：靠左，靠右，居中

• 使用方法

1.设置collection的layout 为 LZTagLayout

 lazy var layout: LZTagLayout = {
        let lay = LZTagLayout()
         lay.itemSpacing = 10
         lay.lineSpacing = 10
         lay.itemHeight = 25
         lay.itemFont = UIFont.systemFont(ofSize: 12)
         lay.itemSpacing = 10
         lay.contentAlignment = .left
         lay.delegate = self
        return lay
    }()

 private(set) lazy var collectionView: UICollectionView = {
       let layout = self.layout
       let temp =  UICollectionView(frame: .zero, collectionViewLayout: layout)
       return temp
   }()

2.正常使用collectionview

collectionView.register(RoundCollectionCell.self, forCellWithReuseIdentifier: "RoundCollectionCell")
        collectionView.register(CollectionHeadView.self, forSupplementaryViewOfKind:UICollectionElementKindSectionHeader , withReuseIdentifier: "CollectionHeadView")
        collectionView.register(UICollectionReusableView.self, forSupplementaryViewOfKind:UICollectionElementKindSectionFooter , withReuseIdentifier: "UICollectionReusableView")
        collectionView.dataSource = self
        collectionView.backgroundColor = .yellow
    
        self.view.addSubview(collectionView)

3.实现UICollectionViewDataSource，cell可根据需求自定义

extension RoundViewController: UICollectionViewDataSource {
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 2
    }
   func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
       return self.titles.count
   }
   func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
       let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "RoundCollectionCell", for: indexPath) as! RoundCollectionCell
       let title = self.titles[indexPath.row]
       cell.fill(title: title)
       return cell
   }
    
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        switch kind {
        case UICollectionElementKindSectionHeader:
            let headView = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "CollectionHeadView", for: indexPath)
            headView.backgroundColor = .systemRed
            return headView
            
        default:
            let footerView = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionFooter, withReuseIdentifier: "UICollectionReusableView", for: indexPath)
            footerView.backgroundColor = .systemOrange
            return footerView
        }
       
    }
}

4.实现LZTagLayout 的 LZTagLayoutDelegate

extension RoundViewController: LZTagLayoutDelegate {
 /// 标签内边距
 func tagLayout(_ layout: LZTagLayout, collectionView: UICollectionView, tagInnerMarginForItemAt indexPath: IndexPath) -> CGFloat {
     return CGFloat(25)
 }
 
  func tagLayout(_ layout: LZTagLayout, collectionView: UICollectionView, sizeForSupplementaryElementOfKind kind: String, at section: Int) -> CGSize {
      switch kind {
      case UICollectionElementKindSectionHeader:
          return CGSize(width: 250, height: 30)
      case UICollectionElementKindSectionFooter:
          return CGSize(width: 250, height: 40)
      default:
          return CGSize(width: 250, height: 40)
      }
     
 }
 
 func tagLayout(_ layout: LZTagLayout, collectionView: UICollectionView, textForItemAt indexPath: IndexPath) -> String {
     return self.titles[indexPath.row]
 }

}

• 版本记录

  1.0.8 secionInset 添加

参考 https://www.jianshu.com/p/47f320732e87