ios - 为什么UILabel TapGesture 只能在标签初始化后工作？

Question

我有以下代码来初始化标签:

let forgotPasswordLabel: UILabel = {
        let label = UILabel()
        label.text = "Forgot password?"
        label.font = ApplicationScheme.instance.containerScheme.typographyScheme.subtitle1
        label.textColor = ApplicationScheme.instance.containerScheme.colorScheme.onPrimaryColor
        label.textAlignment = .right
        label.sizeToFit()
        label.accessibilityRespondsToUserInteraction = true
        label.isUserInteractionEnabled = true
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

后来我将它添加到 subview 中:

let passwordLabel = forgotPasswordLabel
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(onForgotPasswordClick))
passwordLabel.addGestureRecognizer(tapGesture)
self.view.addSubview(passwordLabel)

如果我这样做代码，那么它工作正常，但是如果我将 tapGesture 代码放在标签 forgotPasswordLabel 初始化中，则不会触发点击手势。这是为什么？

不起作用的代码:

let forgotPasswordLabel: UILabel = {
        let label = UILabel()
        label.text = "Forgot password?"
        label.font = ApplicationScheme.instance.containerScheme.typographyScheme.subtitle1
        label.textColor = ApplicationScheme.instance.containerScheme.colorScheme.onPrimaryColor
        label.textAlignment = .right
        label.sizeToFit()
        label.isUserInteractionEnabled = true
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(onForgotPasswordClick))
        label.addGestureRecognizer(tapGesture)
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

这与垃圾收集器有关吗？ UILabel 无法识别的界限？或者是其他东西？

Answer 1

tapGesture在下面的代码中添加了 Closure初始化器，然后将目标分配为 self这是无效的。因为 self这里不是 ViewController

let forgotPasswordLabel: UILabel = {
        let label = UILabel()
        label.text = "Forgot password?"
        label.font = ApplicationScheme.instance.containerScheme.typographyScheme.subtitle1
        label.textColor = ApplicationScheme.instance.containerScheme.colorScheme.onPrimaryColor
        label.textAlignment = .right
        label.sizeToFit()
        label.isUserInteractionEnabled = true
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(onForgotPasswordClick))
        label.addGestureRecognizer(tapGesture)
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

在下面的代码中，tapGesture正在按预期工作，您将目标设置为 self这是ViewController这是有效的。

let forgotPasswordLabel: UILabel = {
    let label = UILabel()
    label.text = "Forgot password?"
    label.font = ApplicationScheme.instance.containerScheme.typographyScheme.subtitle1
    label.textColor = ApplicationScheme.instance.containerScheme.colorScheme.onPrimaryColor
    label.textAlignment = .right
    label.sizeToFit()
    label.accessibilityRespondsToUserInteraction = true
    label.isUserInteractionEnabled = true
    label.translatesAutoresizingMaskIntoConstraints = false
    return label
}()

let passwordLabel = forgotPasswordLabel
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(onForgotPasswordClick))
passwordLabel.addGestureRecognizer(tapGesture)
self.view.addSubview(passwordLabel)

如果是 tapGesture当您设置目标时，它会告诉您在哪里寻找 action当手势发生时