xcode 如何在 Swift 3 中记录函数闭包参数的参数？
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How do you document the parameters of a function's closure parameter in Swift 3?
提问by S?ren Mortensen
In Xcode 8 beta and Swift 3, when you have a method that takes a closure as a parameter, for example:
在 Xcode 8 beta 和 Swift 3 中，当您有一个将闭包作为参数的方法时，例如：
func foo(bar: (String) -> Void) {
bar("Hello, world")
}
How do you document the parameters the closure takes? For example, if I wrote this:
你如何记录闭包所采用的参数？例如，如果我这样写：
/// Calls bar with "Hello, world"
/// - parameter bar: A closure to call
func foo(bar: (String) -> Void) {
bar("Hello, world")
}
Then the quick help looks like this:
然后快速帮助看起来像这样：
I would like to know what the syntax is that will allow me to write some text to replace "No description." Many thanks!
我想知道允许我写一些文本来替换“无描述”的语法是什么。非常感谢！
回答by Tim Vermeulen
As far as I know, you can only document the closure parameters if you label them:
据我所知，如果你给它们贴上标签，你只能记录闭包参数：
/// Calls bar with "Hello, world"
/// - parameter bar: A closure to call
/// - parameter theString: A string to use
func foo(bar: (theString: String) -> Void) {
bar(theString: "Hello, world")
}
This is less than ideal: it forces you to use an argument label when you call the closure, and if there are naming conflicts, there seems no way to distinguish between the two.
这不太理想：它强制您在调用闭包时使用参数标签，并且如果存在命名冲突，似乎无法区分两者。
Edit: As @Arnaud pointed out, you can use _to prevent having to use the parameter label when calling the closure:
编辑：正如@Arnaud 指出的那样，您可以使用_来防止在调用闭包时必须使用参数标签：
/// Calls bar with "Hello, world"
/// - parameter bar: A closure to call
/// - parameter theString: A string to use
func foo(bar: (_ theString: String) -> Void) {
bar("Hello, world")
}
In fact, this is the only valid approach in Swift 3 because parameter labels are no longer part of the type system (see SE-0111).
事实上，这是 Swift 3 中唯一有效的方法，因为参数标签不再是类型系统的一部分（参见SE-0111）。
