Swift 3中的非转义闭包问题 [英] Trouble with non-escaping closures in Swift 3

问题描述

我有一个扩展数组，其形式为：

extension Array
{
    private func someFunction(someClosure: (() -> Int)?)
    {
        // Do Something
    }

    func someOtherFunction(someOtherClosure: () -> Int)
    {
        someFunction(someClosure: someOtherClosure)
    }
}

但是我遇到了错误：将非转义参数'someOtherClosure'传递给期望@escaping闭包的函数。

两个闭包的确没有转义（默认情况下），并显式添加了 @noescape to someFunction 会产生一条警告，表明这是Swift 3.1中的默认设置。

Both closures are indeed non-escaping (by default), and explicitly adding @noescape to someFunction yields a warning indicating that this is the default in Swift 3.1.

我知道为什么

-更新-
屏幕截图：

-- UPDATE -- Screenshot attached:

推荐答案

如前所述，可选闭包是转义。不过，还有一个补充

As already said, Optional closures are escaping. An addition though:

Swift 3.1具有无需实际转义帮助程序功能，该功能在此处很有用。它仅将闭包标记为转义以便在传递的闭包中使用，这样您就不必公开转义

Swift 3.1 has a withoutActuallyEscaping helper function that can be useful here. It marks a closure escaping only for its use inside a passed closure, so that you don't have to expose the escaping attribute to the function signature.

可以像这样使用：

extension Array {

    private func someFunction(someClosure: (() -> Int)?) {
        someClosure?()
    }

    func someOtherFunction(someOtherClosure: () -> Int) {
        withoutActuallyEscaping(someOtherClosure) {
            someFunction(someClosure: $0)
        }
    }
}


let x = [1, 2, 3]

x.someOtherFunction(someOtherClosure: { return 1 })

希望这很有帮助！

这篇关于Swift 3中的非转义闭包问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！