Swift 語言概覽 -自己在Xcode6 動手寫1

Swift是什么？

Swift是蘋果於WWDC 2014發布的編程語言，這里引用The Swift Programming Language的原話：

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.

簡單的說：

1. Swift用來寫iOS和OS X程序。（估計也不會支持其它屌絲系統）
2. Swift吸取了C和Objective-C的優點，且更加強大易用。
3. Swift可以使用現有的Cocoa和Cocoa Touch框架。
4. Swift兼具編譯語言的高性能（Performance）和腳本語言的交互性（Interactive）。

Swift語言概覽

// 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")


// 變量與常量
// Swift 使用 var 聲明 變量 ， let 聲明常量
var myVariable = 42
myVariable = 50
let myConstant = 42

// 類型推導
let explicitDouble : Double = 70

// Swift 不支持隱式 類型轉換 （所以需要顯式類型轉換）
let label = "The width is"
let width = 94
let width1 = label + String(width)

// 使用 \(item) 的形式進行 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."

// 數組和字典
// Swift 使用[] 操作符聲明 數組（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）語法創建空數組和空字典

let emptyArray = String[]()
let emptyDict = Dictionary<String, Float>()

Xcode貼圖