不用xib创建时,需要重写

override init(collectionViewLayout layout: UICollectionViewLayout){}

在调用时需传 UICollectionViewLayout值,不然就会报错

 let layout = UICollectionViewFlowLayout.init()
                
 let vc1 = DataCollectionViewController.init(collectionViewLayout: layout)

接下来就是cell的注册以及调用了

self.collectionView!.register(DataCollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)

 override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of items
        return self.leagueNameArr.count
    }
 override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! DataCollectionViewCell
        cell.titleLabel.text = self.leagueNameArr[indexPath.item]
    
        return cell
    }

如果需要设置item的大小以及距离上左下右的距离就得加上UICollectionViewDelegateFlowLayout协议,并遵循一下方法

  func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize.init(width: 60, height: 30)
    }
    
  func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets.init(top: 5, left: 10, bottom: 5, right: 10)
    }
    

此时,"run"会发现view的背景色是黑色的.我们需要在override init(collectionViewLayout layout: UICollectionViewLayout) {}方法中加上设置背景色

        self.collectionView?.backgroundColor = UIColor.init(red: 237/255, green: 237/255, blue: 237/255, alpha: 1)

下面是collectionViewHeaderView的 基本用法

1.cell注册

        self.collectionView.register(QQGFindHeadCollectionViewCell.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "QQGFindHeadCollectionViewCell")

2.设置高度(两种方法都可以)

  let layout = UICollectionViewFlowLayout()
        layout.headerReferenceSize = CGSize.init(width: WIDTH, height: 300)

   //MARK: - 设置collectView 的每行头部视图高度
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        if self.infoArray.count > 0{
            return CGSize(width: WIDTH, height: 110)
        }
        return CGSize(width: WIDTH, height: 0.001)
        
    }
    

3.设置内容

    //MARK: - 设置collectView的 headerCell内容
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        if self.infoArray.count > 0{
            let cell = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "QQGFindHeadCollectionViewCell", for: indexPath) as! QQGFindHeadCollectionViewCell
            
            
            cell.imageArr = ["https://qqsdg.oss-cn-shenzhen.aliyuncs.com/Userimage_test/19B64825-5410-4D49-92F5-7487ECA750453366901166.jpg","https://qqsdg.oss-cn-shenzhen.aliyuncs.com/Userimage_test/19B64825-5410-4D49-92F5-7487ECA750453366901166.jpg","https://qqsdg.oss-cn-shenzhen.aliyuncs.com/Userimage_test/19B64825-5410-4D49-92F5-7487ECA750453366901166.jpg"]
            
            return cell
        }else{
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "QQGFindHeadCollectionViewCell", for: indexPath) as! QQGFindHeadCollectionViewCell

            return cell
        }
       
    }