ios - 纯代码构建集合但不执行 UICollectionViewDelegateFlowLayout

Question

纯代码(我没有使用 Storyboard ，只是使用代码)构建集合但不执行 UICollectionViewDelegateFlowLayout。

class Calendarview : UIView , UICollectionViewDelegate , UICollectionViewDataSource  , UICollectionViewDelegateFlowLayout {
    var collectionview : UICollectionView!
    override func didAddSubview(_ subview: UIView) {
    }

    override func didMoveToSuperview() {
        let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()

        collectionview = UICollectionView(frame: CGRect(x: 0, y: 0, width: self.bounds.width, height: self.bounds.height) , collectionViewLayout: layout)

        collectionview.frame = self.frame
        collectionview.register(CalendarCell.self, forCellWithReuseIdentifier: "Cell")
        collectionview.dataSource = self
        collectionview.delegate = self
        self.addSubview(collectionview!)
        collectionview.reloadData()
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 42
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
        return CGSize(width: self.bounds.width / 7, height: self.bounds.height / 3)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 5
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return 5
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! CalendarCell
        cell.lbshow = UILabel(frame: cell.bounds)
        cell.lbshow.text = String(indexPath.row)
        cell.addSubview(cell.lbshow)
        cell.backgroundColor = .blue
        return cell
    }
}

Answer 1

将委托(delegate)设置为 self.collectionView.delegate = self;。 UICollectionViewDelegateFlowLayout 继承自 UICollectionViewDelegate。所以它会调用UICollectionViewDelegateFlowLayout的所有方法。

因此，您需要将 self.collectionView.collectionViewLayout 设置为流布局。

        let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
            layout.estimatedItemSize = CGSize(width: 10, height: 10)
            layout.itemSize = CGSize(width: 200, height: 200)
            layout.minimumLineSpacing = 10
            layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
            layout.scrollDirection = .horizontal
            collectionview.collectionViewLayout = layout