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iOS Swift Closures Functions as First Class Citizens Higher Order Functions

Second task is not passing though the answer is correct.

Enable to pass the second task in this challenge , the editor is not suggesting any error and the code is working as expected in playground.

Please advise. below is two answers I tried.

var mathFunction: (Int, Int) -> Int = differenceBetweenNumbers let difference = mathOperation(mathFunction,12,3)


let difference = mathOperation(differenceBetweenNumbers,12,3)

  For this code challenge, let’s define a math operation as a function that 
  carries out some work on two integers and returns an integer as well. An 
  example is the function below, `differenceBetweenNumbers`, which takes two 
  integers and calculates the difference between the numbers. After calculating, 
  it returns the difference.

func differenceBetweenNumbers(a: Int, b:Int) -> (Int) {
  return a - b

// Enter your code below
func mathOperation(differenceBetweenNumbers:(Int,Int) -> (Int),a:Int,b:Int) -> (Int)
    return differenceBetweenNumbers(a,b)
var mathFunction: (Int, Int) -> Int = differenceBetweenNumbers
let difference = mathOperation(mathFunction,12,3)

1 Answer

Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

Task 2:

// The type of “differenceBetweenNumbers" is (Int, Int) - > Int.

- Now that we have a TYPE, we want to create a function that takes in
 this TYPE of function as an argument in its parameter. 
func mathOperation(anyAddFunc: (Int, Int) -> Int, a: Int, b: Int) -> Int{
    return anyAddFunc(a,b)

Task 3:

let difference = mathOperation(differenceBetweenNumbers, 2, 1)

This should work.