Swift - Functions Playground

functions.swift

//: Playground - noun: a place where people can play

import UIKit

func helloWorld() -> Void {
    print("hello, world!")
}

helloWorld()

// ---

func hello(name: String = "world") {
    print("hello, \(name)!")
}

hello(name: "Digital Content")

// ---

func hello(names: String...) {
    
    for name in names {
        print("hello, \(name)!")
    }
    
}

hello(names: "News", "BAU", "Sports")

// ---

var value = 0

func counter(_ count: inout Int) {
    count += 1
}

counter(&value)

// ---

func convert(length: Float) -> (yards: Float, centimeters: Float, meters: Float) {
    
    let yards       = length * 0.0277778
    let centimeters = length * 2.54
    let meters      = length * 0.0254
    
    return (yards, centimeters, meters)
}

convert(length: 10)

// ---

func helloGeneric<T: CustomStringConvertible>(value: T) {
    print("hello, \(value)!")
}

helloGeneric(value: 007)

// ---

func makeViewController<T: RawRepresentable>(from storyboard: T, identifier: T? = nil) -> UIViewController? where T.RawValue == String {
    
    let storyboard = UIStoryboard(name: storyboard.rawValue, bundle: .main)
    
    guard let identifier = identifier else {
        return storyboard.instantiateInitialViewController()
    }
    
    return storyboard.instantiateViewController(withIdentifier: identifier.rawValue)
    
}

// ---

func hello(to name: () -> String) {
    
    let value = name()
    
    print("hello, \(value)!")
    
}

hello(to: { "Matt" })

// ---

func someName() -> String {
    return "Melvin"
}

hello(to: someName)

// ---

func nestedGreeter(name: String) -> Void {
    
    func greet(greeting: String) {
        print("\(greeting), \(name)!")
    }
    
    greet(greeting: "hello")
    
}

nestedGreeter(name: "Rory")

// ---

func greet(greeting: String) -> (_ name: String) -> Void {
    
    return { name in
        print("\(greeting), \(name)!")
    }
    
}

let italianGreeter = greet(greeting: "ciao")
let englishGreeter = greet(greeting: "hello")

italianGreeter("Paolo")
englishGreeter("Paolo")