易采站长站为您分析苹果公司推出的新编程语言Swift简介和入门教程,Swift是苹果于WWDC 2014.6.3发布的编程语言,主要用来替代Objective-C,需要的朋友可以参考下
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.
println("Hello, world")
ar myVariable = 42
myVariable = 50
let myConstant = 42
一、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：
复制代码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：
Swift用来写iOS和OS X程序。（估计也不会支持其它屌丝系统）
Swift吸取了C和Objective-C的优点，且更加强大易用。
Swift可以使用现有的Cocoa和Cocoa Touch框架。
Swift兼具编译语言的高性能（Performance）和脚本语言的交互性（Interactive）。
二、Swift语言概览
1.基本概念
注：这一节的代码源自The Swift Programming Language中的A Swift Tour。
1.1.Hello, world
类似于脚本语言，下面的代码即是一个完整的Swift程序。
println("Hello, world")
1.2.变量与常量
Swift使用var声明变量，let声明常量。
复制代码
ar myVariable = 42
myVariable = 50
let myConstant = 42
1.3.类型推导
Swift支持类型推导（Type Inference），所以上面的代码不需指定类型，如果需要指定类型：
复制代码 let explicitDouble : Double = 70
Swift不支持隐式类型转换（Implicitly casting），所以下面的代码需要显式类型转换（Explicitly casting）：
