总结:swift中的枚举可以看作变量可以作为case匹配参数的类 Enumerations 枚举的作用:状态列举与匹配 枚举值与类型 If a value (known as a “raw” value) is provided for each enumeration case, the value can be a string, a character, or a value of any integer or floating-point type. You can define a c…

原文:Swift语言指南(八)--语言基础之元组 元组 元组(Tuples)将多个值组合为一个复合值.元组内的值可以是任何类型,各个元素不需要为相同类型(各个元素之间类型独立,互不干扰--Joe.Huang). 下例中,(404, "Not Found") 是一个描述HTTP状态码的元组.HTTP状态码是当你向WEB服务器请求页面时服务器返回的一个特殊值,如果你(向WEB服务器)请求了一个不存在的网页,返回的状态码就是 404 Not Found : let http404Error…

1.错误类型与枚举的结合 enum VendingMachineError: Error { case invalidSelection case insufficientFunds(coinsNeeded: Int) case outOfStock } throw VendingMachineError.insufficientFunds(coinsNeeded: 5) 2.异常捕获与栈展开 Error handling in Swift resembles exception handlin…

一.变量定义 1.常量与变量 Use let to make a constant and var to make a variable. 2.类型与推测 However, you don’t always have to write the type explicitly. Providing a value when you create a constant or variable lets the compiler infer its type. 3.类型转换与字符串 Write the…

总结:整个Closure的作用在于简化语言表述形式. 一.闭包的简化 Closure expression syntax has the following general form: { () -> in } reversedNames = names.sorted(by: { (s1: String, s2: String) -> Bool in return s1 > s2 }) Because the sorting closure is passed as an argumen…

一.数据类型 1.基础类型的封装 Swift provides its own versions of all fundamental C and Objective-C types, including Int for integers, Doubleand Float for floating-point values 2.新类型 Swift introduces advanced types not found in Objective-C, such as tuples. Tuples…

1.oc比较: -(BOOL) isKindOfClass: classObj判断是否是这个类或者这个类的子类的实例 -(BOOL) isMemberOfClass: classObj 判断是否是这个类的实例 2.is 类型检查 Use the type check operator (is) to check whether an instance is of a certain subclass type. 3. (as? or as!) 类型转化 Use the conditional f…

Swift defines two kinds of initializers for class types to help ensure all stored properties receive an initial value. These are known as designated initializers and convenience initializers. Designated:指定的:特指的 全初始化与部分初始化 Designated Initializers and…

Overriding A subclass can provide its own custom implementation of an instance method, type method, instance property, type property, or subscript that it would otherwise inherit from a superclass. This is known as overriding. Overriding by accident…

结论:value是拷贝,Reference是引用 Value and Reference Types Types in Swift fall into one of two categories: first, “value types”, where each instance keeps a unique copy of its data, usually defined as a struct, enum, or tuple. The second, “reference types”,…