Can I print function type in Swift?

Question

I want to print the type of a function.

func thanksTo(name: String) {
    print("Thanks, \(name)")
}

printType(thanksTo)    // expected to print "Function (String) -> ()"

Is there any function in Swift that behaves like printType?

Answer 1

Swift 3 and later

As of Swift 3, __FUNCTION__ is deprecated. Instead, use #function in place of __FUNCTION__.

(Thank you, @jovit.royeca.)

---

Swift 2.2 and earlier

You have a few options:

1. print(__FUNCTION__) will output functionName() if the function has no arguments.
2. print(__FUNCTION__) will output functionName (without parentheses) if the function has one or more arguments.

3. print(functionName.dynamicType) will output (() -> Swift.Int) -> Swift.Int for this hypothetical function:

   func functionName(closure: () -> Int) -> Int {
   
   }
   

Thus, to implement the desired functionality for your printType function, you could use a combination of Option 2 and Option 3.