原文：http://kpbp.github.io/swiftcheatsheet/

A quick cheat sheet and reference guide for Apple‘s Swift language. This guide intends to cover all the key features of Swift, including Strings, Arrays, Dictionaries and Flow Control.

Swift is a new programming language for developing iOS and OS X apps that was introduced by Apple in June 2014.

Variables

var myInt = 1var myExplicitInt: Int = 1 // explicit typevar x = 1, y = 2, z = 3 // declare multiple integersmyExplicitInt = 2 // set to another integer value

Constants

let myInt = 1myInt = 2 // compile-time error!

Strings

var myString = "a"let myImmutableString = "c"myString += "b" // abmyString = myString + myImmutableString // abcmyImmutableString += "d" // compile-time error!let count = 7let message = "There are \(count) days in a week"

Logical Operators

var happy = truevar sad = !happy // logical NOT, sad = falsevar everyoneHappy = happy && sad // logical AND, everyoneHappy = falsevar someoneHappy = happy || sad // logical OR, someoneHappy = true

Printing

let name = "swift"println("Hello")println("My name is \(name)")print("See you ")print("later")/*  Hello    My name is swift    See you later */

Arrays

var colors = ["red", "blue"]var moreColors: String[] = ["orange", "purple"] // explicit typecolors.append("green") // [red, blue, green]colors += "yellow" // [red, blue, green, yellow]colors += moreColors // [red, blue, green, yellow, orange, purple]var days = ["mon", "thu"]var firstDay = days[0] // mondays.insert("tue", atIndex: 1) // [mon, tue, thu]days[2] = "wed" // [mon, tue, wed]days.removeAtIndex(0) // [tue, wed]

Dictionaries

var days = ["mon": "monday", "tue": "tuseday"]days["tue"] = "tuesday" // change the value for key "tue"days["wed"] = "wednesday" // add a new key/value pairvar moreDays: Dictionary<string, string=""> = ["thu": "thursday", "fri": "friday"]moreDays["thu"] = nil // remove thu from the dictionarymoreDays.removeValueForKey("fri") // remove fri from the dictionary

Conditionals

//IF STATEMENTlet happy = trueif happy {    println("We‘re Happy!")} else {    println("We‘re Sad :(‘")}// We‘re Happy!let speed = 28if speed <= 0 {    println("Stationary")} else if speed <= 30 {    println("Safe speed")} else {    println("Too fast!")}// Safe speed//SWITCH STATEMENTlet n = 2switch n {case 1:    println("It‘s 1!")case 2...4:    println("It‘s between 2 and 4!")case 5, 6:    println("It‘s 5 or 6")default:    println("Its another number!")}// It‘s between 2 and 4!

For Loops

for var index = 1; index < 3; ++index {	// loops with index taking values 1,2 }for index in 1..3 {	// loops with index taking values 1,2}for index in 1...3 { 	// loops with index taking values 1,2,3}let colors = ["red", "blue", "yellow"]for color in colors {    println("Color: \(color)")}// Color: red// Color: blue// Color: yellow let days = ["mon": "monday", "tue": "tuesday"]for (shortDay, longDay) in days {    println("\(shortDay) is short for \(longDay)")}// mon is short for monday// tue is short for tuesday

While Loops

var count = 1while count < 3 {    println("count is \(count)")    ++count}// count is 1// count is 2count = 1while count < 1 {    println("count is \(count)")    ++count}//count = 1do {    println("count is \(count)")    ++count} while count < 3// count is 1// count is 2count = 1do {    println("count is \(count)")    ++count} while count < 1// count is 1

Functions

func iAdd(a: Int, b: Int) -> Int {  return a + b}iAdd(2, 3) // returns 5func eitherSide(n: Int) -> (nMinusOne: Int, nPlusOne: Int) {  return (n-1, n+1)}eitherSide(5) // returns the tuple (4,6)

Classes

class Counter {  var count: Int = 0   func inc() {     count++  }  func add(n: Int) {    count += n  }  func printCount() {    println("Count: \(count)")  }}var myCount = Counter()myCount.inc()myCount.add(2)myCount.printCount() // Count: 3

[转]Swift Cheat Sheet