Swift 语言概览 -自己在Xcode6 动手写1

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Swift是苹果于WWDC 2014发布的编程语言,这里引用The Swift Programming Language的原话:

Swift is a new programming language for iOS and OS X apps that builds on the best of C and Objective-C, without the constraints of C compatibility.

Swift adopts safe programming patterns and adds modern features to make programming easier, more flexible and more fun.

Swift’s clean slate, backed by the mature and much-loved Cocoa and Cocoa Touch frameworks, is an opportunity to imagine how software development works.

Swift is the first industrial-quality systems programming language that is as expressive and enjoyable as a scripting language.


  1. Swift用来写iOS和OS X程序。(估计也不会支持其它屌丝系统)
  2. Swift吸取了C和Objective-C的优点,且更加强大易用。
  3. Swift可以使用现有的Cocoa和Cocoa Touch框架。
  4. Swift兼具编译语言的高性能(Performance)和脚本语言的交互性(Interactive)。


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

import Cocoa

var str = "Hello, playground"

var str1 = "Hello Wrold!!!"

var str2 = "O(∩_∩)O哈哈~"

// Hello, world

println("Hello, world")

// 变量与常量

// Swift 使用 var 声明 变量 , let 声明常量

var myVariable = 42

myVariable = 50

let myConstant = 42

// 类型推导

let explicitDouble : Double = 70

// Swift 不支持隐式 类型转换 (所以需要显式类型转换)

let label = "The width is"

let width = 94

let width1 = label + String(width)

// 使用 \(item) 的形式进行 字符串格式化

let apples = 3

let orages = 5

let sum = "I have \(apples) apples."

let sum1 = "I have \(apples + orages) pieces of fruit."

// 数组和字典

// Swift 使用[] 操作符声明 数组(array)和字典 (dictionary)

var listArr = ["fish","water","apple","rice"]

listArr[1] = "bottle of water"

var dict = [

"name": "melody",

"age" : "26",


dict["sex"] = "female"

// 一般使用初始化器(initializer)语法创建空数组和空字典

let emptyArray = String[]()

let emptyDict = Dictionary<String, Float>()