Swift 4 - UITapGestureRecognizer 选择器函数未调用

Question

我正在尝试将 "click event" 添加到标签而不是按钮。我没有使用故事板。

[...]

let registerLabel: UILabel = {
    let label = UILabel()
    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(openLoginView))
    tapGesture.numberOfTapsRequired = 1
    label.translatesAutoresizingMaskIntoConstraints = false
    label.text = "Register"
    label.isUserInteractionEnabled = true
    label.addGestureRecognizer(tapGesture)
    label.textColor = Colors.lightGrey
    label.font = label.font.withSize(18)
    return label
}()

[...] // viewDidLoad()

@objc private func openLoginView(sender: UITapGestureRecognizer) {
    print("PRINT ME-->>>>>>>>>")
}

[...]

在 iPhone 6s 模拟器中，当我使用鼠标模拟点击鼠标点击时，控制台内部没有打印任何内容。我错过了什么吗？

Answer 1

您需要延迟声明 registerLabel。像这样：

lazy var registerLabel: UILabel = {
    let label = UILabel(frame: CGRect(x: 200, y: 300, width: 200, height: 50))
    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(openLoginView(sender:)))
    tapGesture.numberOfTapsRequired = 1
    label.translatesAutoresizingMaskIntoConstraints = false
    label.text = "Register"
    label.isUserInteractionEnabled = true
    label.addGestureRecognizer(tapGesture)
    label.textColor = .black
    label.font = label.font.withSize(18)
    return label
}()

此外，如果您需要对 openLoginView 函数中的 sender 执行某些操作，请查看我的选择器。

有关惰性存储属性的更多信息

A lazy stored property is a property whose initial value is not calculated until the first time it is used. You indicate a lazy stored property by writing the lazy modifier before its declaration.

https://docs.swift.org/swift-book/LanguageGuide/Properties.html

希望对您有所帮助！ :)

Swift 4 - UITapGestureRecognizer 选择器函数未调用

Swift 4 - UITapGestureRecognizer selector function not calling

ios

swift4

swift4.2