Ios 如何在集合视图单元格（如App Store）中制作UICollectionView动画？

我如何实现以下目标：

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即使在我滚动浏览时，集合视图也会在集合视图单元格内缓慢移动。

您可以使用

CollectionKit

framework来完成此操作

您还可以在“集合”视图中应用其他一些最佳动画

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这一个属于CollectionView中的单元格。您可以通过调用在单元格中手动设置UIImageView的动画

class func animate(withDuration duration: TimeInterval, 
    animations: @escaping () -> Void)

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您可以找到有关Apple document或stackoverflow的更多信息。

我确实使用desire动画创建了一个简单的项目，我没有实现与AppStore中完全相同的元素位置，但我只向您展示了基本动画以及如何实现它。另外，我没有检查

collectionView

何时到达末尾，我只是用100个元素填充它

我确实添加了

GIF

它的帧速率很低，在模拟器上看起来很好，没有延迟

AnimatedCollectionViewController.swift

class

class AnimatedCollectionViewController: UIViewController {

    @IBOutlet private weak var collectionView: UICollectionView!

    private let identifier = String(describing: AnimatedCollectionViewCell.self)
    private var timer: Timer?

    override func viewDidLoad() {
        super.viewDidLoad()

        /// Loading custom `nib`
        let nib = UINib(nibName: identifier, bundle: Bundle.main)
        collectionView.register(nib, forCellWithReuseIdentifier: identifier)
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        /// Starting animation
        startAutoScrollCardsCollectionView()
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        /// Remove timer from `RunLoop` object
        timer?.invalidate()
        timer = nil // just in case
    }

    private func startAutoScrollCardsCollectionView() {

        /// This method start timer and fire it immediately
        timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [unowned self] _ in
            let currentOffset = self.collectionView.contentOffset
            self.collectionView.setContentOffset(CGPoint(x: currentOffset.x + 5, y: currentOffset.y), animated: true)
        }
    }
}

// MARK: - UICollectionViewDataSource extension

extension AnimatedCollectionViewController: UICollectionViewDataSource {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 100
    }

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

// MARK: - UICollectionViewDelegateFlowLayout extension

extension AnimatedCollectionViewController: UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: 100, height: 100)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets(top: 20, left: 0, bottom: 20, right: 0)
    }
}

class AnimatedCollectionViewCell: UICollectionViewCell {

    override func awakeFromNib() {
        super.awakeFromNib()

        contentView.backgroundColor = UIColor.random
        contentView.layer.cornerRadius = 20
    }
}

extension CGFloat {
    static func random() -> CGFloat {
        return CGFloat(arc4random()) / CGFloat(UInt32.max)
    }
}

extension UIColor {
    static var random: UIColor {
        return UIColor(red:   .random(),
                       green: .random(),
                       blue:  .random(),
                       alpha: 1.0)
    }
}

虚拟

AnimatedCollectionViewCell.swift

class

class AnimatedCollectionViewController: UIViewController {

    @IBOutlet private weak var collectionView: UICollectionView!

    private let identifier = String(describing: AnimatedCollectionViewCell.self)
    private var timer: Timer?

    override func viewDidLoad() {
        super.viewDidLoad()

        /// Loading custom `nib`
        let nib = UINib(nibName: identifier, bundle: Bundle.main)
        collectionView.register(nib, forCellWithReuseIdentifier: identifier)
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        /// Starting animation
        startAutoScrollCardsCollectionView()
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        /// Remove timer from `RunLoop` object
        timer?.invalidate()
        timer = nil // just in case
    }

    private func startAutoScrollCardsCollectionView() {

        /// This method start timer and fire it immediately
        timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [unowned self] _ in
            let currentOffset = self.collectionView.contentOffset
            self.collectionView.setContentOffset(CGPoint(x: currentOffset.x + 5, y: currentOffset.y), animated: true)
        }
    }
}

// MARK: - UICollectionViewDataSource extension

extension AnimatedCollectionViewController: UICollectionViewDataSource {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 100
    }

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

// MARK: - UICollectionViewDelegateFlowLayout extension

extension AnimatedCollectionViewController: UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: 100, height: 100)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets(top: 20, left: 0, bottom: 20, right: 0)
    }
}

class AnimatedCollectionViewCell: UICollectionViewCell {

    override func awakeFromNib() {
        super.awakeFromNib()

        contentView.backgroundColor = UIColor.random
        contentView.layer.cornerRadius = 20
    }
}

extension CGFloat {
    static func random() -> CGFloat {
        return CGFloat(arc4random()) / CGFloat(UInt32.max)
    }
}

extension UIColor {
    static var random: UIColor {
        return UIColor(red:   .random(),
                       green: .random(),
                       blue:  .random(),
                       alpha: 1.0)
    }
}

---

所以基本上发生的是，我启动一个

计时器

并立即启动。这个计时器调用

completion

0.1秒，在此完成时间内，我更改

setContentOffset.x

收集视图的位置

您可以从这里开始，将自定义布局添加到单元格的位置，并在

collectionView

reach end时进行检查