Swift 语言概览 -自己在Xcode6 动手写1

时间:2023-03-08 16:08:44

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

Swift 语言概览 -自己在Xcode6 动手写1