博客

最近在做项目的时候用到了，系统默认UICollectionViewController，一般写的时候用的都是UICollectionView，这次用UICollectionViewController遇到了一些问题记录一下

1.不用xib创建时,需要重写

override init(collectionViewLayout layout: UICollectionViewLayout){
    
     super.init(collectionViewLayout: layout)
    
    }

重写后会自动提示添加下面这段函数，这段函数是swift4.0以后都自动提示要加的

 required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

2.最重要的是layout不能写到viewDidLoad()这样是无效的

 override func viewDidLoad() {
        super.viewDidLoad()

    
       let layout = UICollectionViewFlowLayout()
        layout.itemSize = CGSize(width: UIScreen.main.bounds.width-20 , height: UIScreen.main.bounds.height-20)
        layout.minimumLineSpacing = 15.0
        layout.minimumInteritemSpacing = 0
        layout.scrollDirection = .horizontal

这样是无效的

必须在convenience init()方法里声明

convenience init() {
        let layout = UICollectionViewFlowLayout()
        layout.itemSize = CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
        layout.minimumLineSpacing = 15.0
        layout.minimumInteritemSpacing = 0
        layout.scrollDirection = .horizontal
        self.init(collectionViewLayout: layout)

    }

接下来就是cell的注册以及调用了

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

设置返回layout的个数和cell的内容

 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)
    }