更改所选UICollectionView单元的大小

Question

我有一个简单的UICollectionViewController,它返回X个单元格.我想拥有它,所以当选择一个单元格时,特定的选定单元格将改变它的大小并变得更大,因为所有其他单元格保持不变.我该如何实现这一目标？这是我的代码:

class HomeController: UICollectionViewController, UICollectionViewDelegateFlowLayout {

    let cellId = "cellId"

    override func viewDidLoad() {
        super.viewDidLoad()
        collectionView?.backgroundColor = UIColor(white: 0.90, alpha: 1.0)

        collectionView?.register(PostCell.self, forCellWithReuseIdentifier: cellId)
        collectionView?.showsVerticalScrollIndicator = false
        collectionView?.alwaysBounceVertical = true
    }

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

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! PostCell
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let height = (view.frame.width) * 9 / 16
        return CGSize(width: view.frame.width, height: height + 50 + 50)
    }
}

Answer 1

您可以检查是否选择了indexPath来自sizeForItemAt.如果是,则返回不同的高度,否则返回标准高度.

override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    collectionView.performBatchUpdates(nil, completion: nil)
}

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

    switch collectionView.indexPathsForSelectedItems?.first {
    case .some(indexPath):
        return CGSize() // your selected height
    default:
        let height = (view.frame.width) * 9 / 16
        return CGSize(width: view.frame.width, height: height + 50 + 50)
    }
}