swift - ios - Swift 4 : How to remove UIImageViews when UIImageView. 动画图像完成了吗？

Question

我在我的项目中使用 .animationImages 作为 UIImageViews(这是一个游戏)。当用户按下提示按钮时，我以编程方式创建数量可变的 UIImageView，这些 View 将出现在屏幕上并播放相同的图像序列一次。当动画停止时，我需要从 View 中删除 UIImageViews，但我不知道如何执行此操作。

我已经浏览了 .animationImages 和 .startAnimating 的快速文档，但它实际上只是一个段落和一行，两者都与完成或完成通知等无关。任何帮助将不胜感激。

private func hideAnswerButtonsHint() {

    // Clear all of the answer boxes that aren't hint locked
    resetAnswerBoxes()

    var imageArray = [UIImage]()
    var remainingLetters = [String]()

    for imageCount in 1...8 {
        let imageName = "green_smoke_puff_0\(imageCount)"
        let image = UIImage(named: imageName)!
        imageArray.append(image)
    }

    for answerBox in answerBoxArray where answerBox.hintLock == false {
        if let letter = answerBoxDict[answerBox.tag] {
            remainingLetters.append(letter)
        }
    }

    for answerButton in answerButtonArray where answerButton.hintLock == false {
        if let index = remainingLetters.index(of: answerButton.titleText) {
            answerButton.decompress()
            remainingLetters.remove(at: index)
        } else {
            let frame = answerButton.superview?.convert(answerButton.frame.origin, to: nil)

            let imageView = UIImageView()
            imageView.animationImages = imageArray
            imageView.animationDuration = 0.5
            imageView.animationRepeatCount = 1
            imageView.frame = CGRect(x: frame!.x, y: frame!.y, width: answerButton.frame.width, height: answerButton.frame.height)

            view.addSubview(imageView)
            imageView.startAnimating()

            answerButton.compress()
            answerButton.hintLock = true
        }
    }
}

Answer 1

UIImageView 是一个 NSObject，因此您始终可以使用 KVO查看其属性:

    var observation: NSKeyValueObservation?
    override func viewDidLoad() {
        super.viewDidLoad()
        observation = imageView.observe(\.isAnimating) { [weak self] imageView, change in
            if let value = change.newValue,
               value == true {
                imageView.removeFromSuperview()
                self?.observation = nil
            }
        }
    }