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iOS Closures in Swift First Class Functions Higher Order Functions

Make sure you return the result of applying the function argument on self

that's not what Im doing for sure

// Enter your code below

extension String {

func transform((String) -> String) -> String {

return self


1 Answer

Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

First off, it looks like you missed the parameter label for the method's closure parameter.

About your question on applying the closure to self. To apply a method or function to a variable means to pass the variable into the method/function as a parameter. For example, when you use the print function, you are applying that function to whatever you print with it:

print("Hello World")
// Applying `print` to the string, "Hello World"