Swift中 struct 和 class 的区别

类和结构体的相同点：

a、属性
b、方法
c、下标操作
d、构造器
e、扩展
f、协议

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Structures and classes in Swift have many things in common. Both can:

• Define properties to store values
• Define methods to provide functionality
• Define subscripts to provide access to their values using subscript syntax
• Define initializers to set up their initial state
• Be extended to expand their functionality beyond a default implementation
• Conform to protocols to provide standard functionality of a certain kind

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类和结构体的不同点：

a、类具有：继承、析构、类型转换、引用计数
b、类和结构体在内存中的实现机制的不同：类存储在堆(heap)中，结构体存储在栈(stack)中
c、类是引用类型，而结构体是值类型

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Classes have additional capabilities that structures don’t have:

• Inheritance enables one class to inherit the characteristics of another.
• Type casting enables you to check and interpret the type of a class instance at runtime.
• Deinitializers enable an instance of a class to free up any resources it has assigned.
• Reference counting allows more than one reference to a class instance.

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如何选择：

a、默认情况下使用structures。
b、当您需要Objective-C互操作性时，请使用classes。
c 、当您需要控制建模数据的标识时，请使用classes。
d 、通过共享实现，使用structures和协议来采用行为。

Consider the following recommendations to help choose which option makes sense when adding a new data type to your app.

• Use structures by default.
• Use classes when you need Objective-C interoperability.
• Use classes when you need to control the identity of the data you're modeling.
• Use structures along with protocols to adopt behavior by sharing implementations.

struct Student {
    //  MARK: - 属性
    var name: String
    var age: Int
    var classNum: String
    
    //  MARK: - 方法
    func descriptionStudent() {
        print("姓名：" + name + " 年龄：" + "\(age)" + " 班级号：" + classNum)
        // self.name = "alice"
    }
    
    mutating func modifyName(name: String){
        self.name = name
    }
}

var student1 = Student(name: "andy", age: 15, classNum: "0501")
student1.descriptionStudent()

// 输出：
// 姓名：Andy 年龄：15 班级号：0501
// 姓名：Bob 年龄：15 班级号：0501