自定义单元格和每个自定义高度

Question

我通过开关功能输出4个自定义单元格现在我需要为每个单元格输出动态高度值或固定高度值。我喜欢两者，因为它们的高度总是静止的。

我订阅了uiСollectionviewВelegateFlowLayout协议并找到了如何改变所有细胞的高度

func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {
        let size = CGSize(width: 357, height: 600)
        return size

覆盖我使用该函数的单个单元格的高度

cell.frame = CGRect(cell.frame.origin.x, cell.frame.origin.y, width: 100.0, height: 100.0)

但它不起作用，“表达式类型'@lvalue CGRect'在没有更多上下文的情况下是模棱两可的”

在这种情况下我该怎么办？用什么功能？

完整代码如下

// main protocols UICollectionView
extension ViewController: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {

    // width and height for cell in collectionView
    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {
        let size = CGSize(width: 357, height: 600)
        return size
    }


    //margins for cell in collectionView
    func collectionView(_ collectionView: UICollectionView, layout
        collectionViewLayout: UICollectionViewLayout,
                        minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 40.0
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 4
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {


            var cell: UICollectionViewCell!

            switch indexPath.row {
            case 1:
                cell = collectionView.dequeueReusableCell(withReuseIdentifier: "secondCell", for: indexPath)
                    as? secondCollectionViewCell
                cell.frame = CGRect(cell.frame.origin.x, cell.frame.origin.y, width: 100.0, height: 100.0)

            case 2:
                cell = collectionView.dequeueReusableCell(withReuseIdentifier: "thirdCell", for: indexPath)
                    as? cellThirdCollectionViewCell

            case 3:
                cell = collectionView.dequeueReusableCell(withReuseIdentifier: "fourthCell", for: indexPath)
                    as? fourthCollectionViewCell

            default:
                cell = collectionView.dequeueReusableCell(withReuseIdentifier: "imageCell", for: indexPath)
                    as? imageModelCollectionViewCell
            }
            return cell
        }
    }

Answer 1

extension ViewController : UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        switch indexPath.row {
        case 1:
            return CGSize(width: 100, height: 200)
        case 2:
            return CGSize(width: 100, height: 300)
        case 3:
            return CGSize(width: 100, height: 400)
        default:
            return CGSize(width: 100, height: 100)
        }
    }
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        var cell: UICollectionViewCell!

        switch indexPath.row {
        case 1:
            cell = collectionView.dequeueReusableCell(withReuseIdentifier: "firstCell", for: indexPath)
                as? firstCollectionViewCell


        case 2:
            cell = collectionView.dequeueReusableCell(withReuseIdentifier: "secondCell", for: indexPath)
                as? secondCollectionViewCell

        case 3:
            cell = collectionView.dequeueReusableCell(withReuseIdentifier: "thirdCell", for: indexPath)
                as? thirdCollectionViewCell

        default:
            cell = collectionView.dequeueReusableCell(withReuseIdentifier: "imageCell", for: indexPath)
                as? imageModelCollectionViewCell
        }
        return cell
    }
}

完全解决了不要忘记添加的问题

override func viewDidLoad() {
    super.viewDidLoad()
    collectionView.delegate = self
}

附：如果你得到“collectionView.delegate = self”错误，可能是因为你在viewController而不是collectionViewController中工作

你需要添加IBOutlet

Answer 2

你有没有尝试将你的功能func collectionView(_:layout:sizeForItemAt:)改为这样的？

let cellHeights = [ 90, 400, 100, 70 ]

// width and height for cell in collectionView
func collectionView( _ view: UICollectionView, 
                     layout collectionViewLayout: UICollectionViewLayout,
                     sizeForItemAt indexPath: IndexPath ) -> CGSize 
{
    return CGSize( 
        width: view.bounds.size.width, 
        height: cellHeights[indexPath.row] 
    )
}

此外，将collectionView.dequeueReusableCell(withReuseIdentifier:for:)的结果转换为UICollectionViewCell子类对您的代码没有影响...

我可能会改为：

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell 
{
    // map row numbers to cell reuse identifiers...   
    let ids = [ 
        0: "secondCell", 
        1: "thirdCell", 
        2: "fourthCell" 
    ]

    // look up the reuse identifier for the row we want; if none found (subscript call returns `nil`), use `"imageCell"`
    let reuseID = ids[indexPath.row] ?? "imageCell"
    let cell = collectionView.dequeueReusableCell( withReuseIdentifier: reuseID, for: indexPath)

    return cell
}

Answer 3

您可以使用高度数组并根据indexPath检索单元格高度。

let heightArray = [90,400,100,70]

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

                return CGSize(width: 357, height: heightArray[indexPath.row])

        }