Søren Mortensen Søren Mortensen - 4 months ago 13
Swift Question

How do you document the parameters of a function's closure parameter in Swift 3?

In Xcode 8 beta and Swift 3, when you have a method that takes a closure as a parameter, for example:

func foo(bar: (String) -> Void) {
bar("Hello, world")
}


How do you document the parameters the closure takes? For example, if I wrote this:

/// 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:

foo(bar:) Quick Help

I would like to know what the syntax is that will allow me to write some text to replace "No description." Many thanks!

Answer

As far as I know, you can only document the closure parameters if you label them:

/// 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.

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