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iOS Swift Closures Functions as First Class Citizens Higher Order Functions

Foto Graft
PLUS
Foto Graft
Courses Plus Student 2,601 Points

Closures

I think I don't understand what the question is asking. Can someone help me with this? I tried to let the function take in another function but it doesn't seem to work either.

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 () -> (Int, Int) -> (Int) {
    return differenceBetweenNumbers
}

3 Answers

Caleb Kleveter
MOD
Caleb Kleveter
Treehouse Moderator 37,862 Points

Here is a code example from the docs:

func printMathResult(mathFunction: (Int, Int) -> Int, a: Int, b: Int) {
    println("Result: \(mathFunction(a, b))")
}
printMathResult(addTwoInts, 3, 5)
// prints "Result: 8"
Foto Graft
PLUS
Foto Graft
Courses Plus Student 2,601 Points

Thanks! I re-read the docs and solved it! Here's mine:

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) }