diff --git a/a_swift_tour.html b/a_swift_tour.html index f0e44fe1..27a20f18 100644 --- a/a_swift_tour.html +++ b/a_swift_tour.html @@ -15,6 +15,8 @@ + + @@ -44,7 +46,7 @@ -
通常来说,编程语言教程中的第一个程序应该在屏幕上打印“Hello, world”。在Swift中,可以用一行代码实现:
@@ -198,7 +228,7 @@注意:为了获得最好的体验,在Xcode当中使用代码预览功能。代码预览功能可以让你编辑代码并实时看到运行结果。
使用let来声明常量,使用var来声明变量。一个常量的值在编译时并不需要获取,但是你只能为它赋值以此。也就是说你可以用常量来表示这样一个值:你只需要决定一次,但是需要使用很多次。
使用let来声明常量,使用var来声明变量。一个常量的值在编译时并不需要获取,但是你只能为它赋值一次。也就是说你可以用常量来表示这样一个值:你只需要决定一次,但是需要使用很多次。
var myVariable = 42
myVariable = 50
let myConstant = 42
@@ -699,9 +729,11 @@ anyCommonElements([1, 2, 3], [3])
Swift是iOS和OS X应用开发的一门新雨燕。然而,如果你有C或者Objective-C开发经验的话,你会发现Swift的很多内容都是你熟悉的。
+Swift的类型是在C和Objective-C的基础上提出的,Int是整型;Double和Float是浮点型;Bool是布尔型;String是字符串。Swift还有两个有用的集合类型,Array和Dictionary,具体内容在集合类型(待添加连接)一章中。
就像C语言一样,Swift使用变量来进行存储并通过变量名来关联值。在Swift中,值不可变的变量有着广泛的应用,它们就是常量,而且比C语言的常量更强大。在Swift中,如果你要处理的值不需要改变,那使用常量可以让你的代码更加安全并且更好地表达你的意图。
+除了我们熟悉的类型,Swift还增加了Objective-C中没有的类型比如元组(Tuple)。元组可以让你创建或者传递一组数据,比如作为函数的返回值时,你可以用一个元组可以返回多个值。
+Swift还增加了可选(Optional)类型,用于处理值缺失的情况。可选表示“那儿有一个值,并且它等于x”或者“那儿没有值”。可选有点像在Objective-C中使用nil,但是它可以用在任何类型上,不仅仅是类。可选类型比Objective-C中的nil指针更加安全也更具表现力,它是Swift许多强大特性的重要组成部分。
Swift是一个类型安全的语言,可选就是一个很好的例子。Swift可以让你清楚地知道值的类型。如果你的代码期望得到一个String,类型安全会阻止你不小心传入一个Int。你可以在开发阶段尽早发现并修正错误。
常量和变量把一个名字(比如maximumNumberOfLoginAttempts或者welcomeMessage)和一个指定类型的值(比如数字10或者字符串Hello)联系起来。常量的值一旦设定就不能改变,而变量的值可以随意更改。
(未完)
+ + +Swift是苹果在WWDC2014上发布的一款全新的编程语言,本书译自苹果官方的Swift教程《The Swift Programming Language》。
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@@ -213,7 +241,7 @@ - + diff --git a/swift/swift.html b/swift/swift.html index 95887308..a51fa9c2 100644 --- a/swift/swift.html +++ b/swift/swift.html @@ -46,7 +46,7 @@ -