Closure Expressions

Closure Expressions.swift

func doubler(i: Int) -> Int {
    return i * 2
}

let doubleFunction = doubler

doubleFunction(2)

let numbers = [1,2,3,4,5]
let doubleNumbers = numbers.map(doubleFunction)

/***************/

let tripledNumbers = numbers.map({ (i: Int) -> Int in return i * 3 })

// Rule #2: Inferring Type From Context

numbers.map({ i in return i * 3 })

// Rule #3: Implicit Returns from Single-Expression Closures

numbers.map({ i in i * 3 })

// Rule #4: Shorthand Argument Names

numbers.map({ $0 * 3 })

// Rule #5: Trailing Closures

numbers.map() { $0 * 3 }

/***************/

[1,2,3,4,5].map() {
    (digit: Int) -> Int in
    
    if digit % 2 == 0 {
        return digit / 2
    } else {
        return digit
    }
}

/***************/

// Rule #6: Ignoring Parentheses

numbers.map { $0 * 3 }