I found this in some open source code.

I am familiar with map(), but not the CGFloat.init(_:)) part.

The Swift code is as follows:

if let array = propertyListValue as? [Int], array.count == 3 || array.count == 4 {
        let floats = array.map(CGFloat.init(_:))
}

Not sure what to look for in docs. I know what _ name : Type means in a function declaration... but just confused by this use case.

CodePudding user response：

map takes one argument, a function that accepts an argument of the sequence element type and returns any type. CGFloat.init is the name of (technically a reference to) just such a function.

Perhaps you think of map as taking a "closure", and indeed you could equivalently have said

map { CGFloat($0) }

here; but that's in fact exactly the same sort of function — it's just that instead of the function's name (reference) you're supplying its body.