ios - 为什么在为 UIView 设置动画时没有调用我的 UITapGestureRecognizer？

Question

我用 UIImageView 做了一个 toast View 在其中，我想要做的是每次用户点击 ImageView 时， toast 都会自行解除。自然我配置了一个UITapGestureRecognizer到我的 ImageView ，但没有调用选择器函数。这是我所做的:

class ToastView: UIView {

    private var icon: UIImageView!

    init() {
        super.init(frame: .zero)
        setupViews()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupViews()
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        setupConstraints()
    }

    private func setupViews() {
        translatesAutoresizingMaskIntoConstraints = false
        layer.cornerRadius = 8
        isUserInteractionEnabled = true
  
        icon = UIImageView()
        icon.translatesAutoresizingMaskIntoConstraints = false
        icon.image = UIImage(named: "someImage")
        icon.isUserInteractionEnabled = true
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(iconHandler))
        icon.addGestureRecognizer(tapGesture)
        addSubview(icon)
    }

    private func setupConstraints() {
        NSLayoutConstraint.activate([
            topAnchor.constraint(equalTo: superview!.topAnchor, constant: 55),
            leadingAnchor.constraint(equalTo: superview!.leadingAnchor, constant: 16),
            trailingAnchor.constraint(equalTo: superview!.trailingAnchor, constant: -16),
            icon.heightAnchor.constraint(equalToConstant: 16),
            icon.widthAnchor.constraint(equalToConstant: 16),
            icon.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -16),
            icon.centerYAnchor.constraint(equalTo: centerYAnchor),
        ])
    }

    @objc private func iconHandler(_ sender: UITapGestureRecognizer) {
        // This function is not called
        print("handle icon")
    }
}

经过一番研究，我试图给 ToastView手势识别器而不是 ImageView 。所以在我的自定义 UIViewController 中显示 Toast 时，我确实提供了点击手势识别器像这样的类:

class CustomViewController: UIViewController {
    private var isShowingToast: Bool = false
    private lazy var toast: ToastView = {
        let toast = ToastView()
        toast.isUserInteractionEnabled = true
        toast.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(dismissToast)))
        return toast
    }()

    func showToastWithMessage() {
        if !isShowingToast {
            view.addSubview(toast)
            UIView.animate(withDuration: 0.5, delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 1.0, options: .curveEaseInOut, animations: { [weak self] in
                self?.toast.alpha = 1
                self?.toast.frame.origin.y += 10
                self?.isShowingToast = true
            }, completion: { _ in
                UIView.animate(withDuration: 0.5, delay: 5.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 1.0, options: .curveEaseInOut, animations: { [weak self] in
                    self?.toast.alpha = 0
                    self?.toast.frame.origin.y -= 10
                }, completion: { [weak self] _ in
                    self?.isShowingToast = false
                    self?.toast.removeFromSuperview()
                })
            })
        }
    }
    
    @objc private func dismissToast() {
        // This functions does not get called as well
        print("dismiss")
    }
}

不幸的是，dismiss 函数不会打印到控制台。有没有办法解决这个问题？

Answer 1

看起来这是由于您的动画而发生的。 View 始终处于动画状态并阻止点击手势。您可以尝试使用延迟调用它，而不是为您的动画添加延迟。

func showToastWithMessage() {
    if !isShowingToast {
        view.addSubview(toast)
        UIView.animate(withDuration: 0.5, delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 1.0, options: .curveEaseInOut, animations: { [weak self] in
            self?.toast.alpha = 1
            self?.toast.frame.origin.y += 10
            self?.isShowingToast = true
        }, completion: { _ in
            print("Completion")
        })

        DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
            UIView.animate(withDuration: 0.5, delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 1.0, options: .curveEaseInOut, animations: { [weak self] in
                self?.toast.alpha = 0
                self?.toast.frame.origin.y -= 10
            }, completion: { [weak self] _ in
                self?.isShowingToast = false
                self?.toast.removeFromSuperview()
            })
        }

    }
}

这样 View 会在 5 秒后进入动画状态，而不是 5 秒延迟。