ios - 在 UILabel 上添加关闭操作

Question

我想在用户点击 UILabel 时添加一个闭包:

class ActionLabel: UILabel {
    typealias DidTapLabel = (ActionLabel) -> ()

    private let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(didTouchUpInside(sender:)))

    var didTouchUpInside: DidTapLabel? {
        didSet {
            if didTouchUpInside != nil {
                self.addGestureRecognizer(tapGestureRecognizer)
                self.isUserInteractionEnabled = true
            } else {
                self.removeGestureRecognizer(tapGestureRecognizer)
                self.isUserInteractionEnabled = false
            }
        }
    }

    // MARK: - Actions
    @objc func didTouchUpInside(sender: ActionLabel) {
        if let handler = didTouchUpInside {
            handler(self)
        }
    }
}

用法:

    label.didTouchUpInside = { [weak self] sender in
        guard let strongSelf = self else {return}
        print(strongSelf)
    }

但是好像不行

Answer 1

您不能使用对 self 的引用来初始化手势识别器，因为此时初始化尚未完成。打印手势识别器数组显示 target 未设置的信息

addGestureRecognizer(tapGestureRecognizer)
print("\(gestureRecognizers)")

输出(看行尾)

Optional([<UITapGestureRecognizer: 0x6000001f9600; state = Possible; view = <asdfefe.ActionLabel 0x7fd714a03ea0>; target= <(action=didTouchUpInside:, target=<(null) 0x0>)>>])

因此，为了解决这个问题，您可以在初始化调用中初始化手势识别器

private var tapGestureRecognizer:UITapGestureRecognizer!

override init(frame: CGRect) {
    super.init(frame: frame)
    tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(didTouchUpInside))
}

希望对您有所帮助:)