Error: "Cannot assign to immutable expression of type 'Bool'"?

Question

我该如何解决这个问题？我是一个新的编码器。谢谢

我收到以下错误：

"Cannot assign to immutable expression of type 'Bool'"

当我尝试将 "isSelected" 设置为 false 和 true

@IBAction func onFilter(_ sender: Any) {

    if ((sender as AnyObject).isSelected == true) {

        hideSecondaryMenu()
        (sender as AnyObject).isSelected = false

    } else {

        showSecondaryMenu()
        (sender as AnyObject).isSelected = true

    }
}

Answer 1

您收到此错误是因为当您将发件人转换为 AnyObject 时，您得到的是 immutable 类型的对象，因此您无法更新其属性，解决问题的最佳选择是更改您的从 Any 到实际 UIControl 的发件人声明意味着如果它是按钮则 UIButton。

@IBAction func onFilter(_ sender: UIButton) {
    hideSecondaryMenu()
    sender.isSelected = !sender.isSelected
}

如果您仍想使用 Any，则将发件人转换为它所属的实际 UIControl。

@IBAction func onFilter(_ sender: Any) {
    if sender is UIButton {
         let btn = sender as! UIButton
         hideSecondaryMenu()
         btn.isSelected = !btn.isSelected
    }
}

Error: "Cannot assign to immutable expression of type 'Bool'"?

Error: "Cannot assign to immutable expression of type 'Bool'"?

xcode

immutability

sender

swift3