Swift 语言概览 -自己在Xcode6 动手写1

原文:Swift 语言概览 -自己在Xcode6 动手写1

Swift是什么？

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.

简单的说：

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）。

Swift语言概览

// 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 =
myVariable =
let myConstant = 
 
// 类型推导
let explicitDouble : Double = 
 
// 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 =
let width1 = label + String(width)
 
// 使用 \(item) 的形式进行 字符串格式化
let apples =
let orages =
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[] = "bottle of water"
 
var dict = [
    "name": "melody",
    "age" : "",
 
]
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>()

Xcode贴图