如何在Swift中展开这个可选项,更优雅一点？

Question

解包选项可以通过几种不同的方式完成,但我发现自己只使用一种方式.

func keyboardDidShow(keyboardRect: CGRect?) {
    var height: CGFloat?
    if let rectHeight = keyboardRect?.height {
        height = rectHeight
    } else {
        height = 0
    }
    let insets = UIEdgeInsets(top: 0, left: 0, bottom: height!, right: 0)

    ///...clipping rest of method
}

你会如何减少这里的线数？

Answer 1

在此特定示例中,您可以使用nil-coalescing运算符 ??:

func keyboardDidShow(keyboardRect: CGRect?) {
    let height = keyboardRect?.height ?? 0
    let insets = UIEdgeInsets(top: 0, left: 0, bottom: height, right: 0)

    ///...clipping rest of method
}