[Swift] Closure 1

_{A rundown of most of the forms used with closures}

_{1. The most basic way to pass a function}
_{2. Basic closure}
_{3. Trailing closure}
_{4. Forms that can be simplified}



func backwards(first: String, second: String) -> Bool {
    print("\(first) \(second) 비교중")
    return first > second
}
let names = ["wizplan", "eric", "yagom", "jenny"]


// Original
let Original = names.sorted(by: backwards(first:second:))



// Basic closure
let basicClosure: [String] = names.sorted(by: {
    (first: String, second: String) -> Bool in
    return first > second
})



// Trailing closure 1
let trailingClosure = names.sorted() {
    (first: String, second: String) -> Bool in return first > second
}
// Parentheses can be omitted too
let trailingClosure2 = names.sorted {
    (first: String, second: String) in return first > second
}

// Multiple trailing closures
func multipleTrailing(a: (String) -> Void, b: (Int) -> Void, c: (Double) -> Int) {}

let multipleTrailingClousure = multipleTrailing
{ (x: String) in
    // contents
} b: { (x: Int) in
    // contents
} c: { (x: Double) in
    // contents
    return 3
}



// Simplifying closure expressions

// Type inference
let inferType = names.sorted {
    (first, second) in return first > second
}

// Shorthand arguments
let shorthandArgument = names.sorted {
    return $0 > $1
}

// Omitting the return type
let implicitReturn = names.sorted {
    $0 > $1
}

// Operator function
let operatorFunction = names.sorted(by: >)

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