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iOS Swift Closures Functions as First Class Citizens Higher Order Functions

Posted by Tim Polehn
Tim Polehn
7,461 Points

I can make this code work on Xcode but it will not work on your test what am I missing?

// Enter your code below

func mathOperation(mathoporation: ((Int), (Int)) -> (Int), x:(Int), y:(Int)) -> (Int){ return mathoporation(x, y) }

let x: (Int) = 5 let y: (Int) = 7 let difference = mathOperation(differenceBetweenNumbers, x, y)

higherOrderFunctions.swift 
/** 
  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(mathoporation: ((Int), (Int)) -> (Int), x:(Int), y:(Int)) -> (Int){
    return mathoporation(x, y)
}

let x: (Int) = 5
let y: (Int) = 7
let difference = mathOperation(differenceBetweenNumbers, x, y)

1 Answer

Jhoan Arango
Jhoan Arango
14,575 Points
Jhoan Arango
Jhoan Arango
14,575 Points

Hello Tim:

Out of curiosity, is there any particular reason why you are putting parenthesis in all the Int Types ?

I ask you this, because I have seen it done before, and I am wondering if that’s coming from another language, or Objective-C.

Try the code below, this might let you pass the challenge. 

func mathOperation(mathoporation: (Int, Int) -> Int, x: Int, y: Int) -> Int {
    return mathoporation(x, y)
}

let difference = mathOperation(differenceBetweenNumbers, 7, 5)