Swift Closures

ClosuresPlayground.swift

import UIKit

var simpleClosure = {
    print("Hello from a closure!")
}

simpleClosure()

var wrapperColosure = {
    let outerVariable = "Jon"
    let innerClosure = {
        print("Hello \(outerVariable)!")
    }
    
    innerClosure()
}

wrapperColosure()

var greeterClosure = {(name: String) -> String in
    "Hello \(name)!"
}

greeterClosure("Jon")

var doubleAmount = {(number: Int) -> Int in
    number * 2
}

print(doubleAmount(2))

func computation(n: Int, closure: (_ num: Int) -> Int) {
    print("The original value is \(n)")
    print("We apply a extra computation...")
    let newValue = closure(n)
    print("We end our computation: \(newValue)")
}

computation(n: 2) { (num: Int) -> Int in
    num + num
}

computation(n: 3) { num in
    num * 3
}

computation(n: 4) {
    $0 * 4
}

func multiply(multiplier: Int) -> (Int) -> Int {
    let mul = multiplier
    
    return { num in
        return mul * num
    }
}

var timesTwo = multiply(multiplier: 2)
print(timesTwo(5))

var timesTen = multiply(multiplier: 10)
print(timesTen(5))