这个问题似乎是重复的，但无论如何，下面的问题将回答大多数用例:

One of the most important differences between structures and classes is that structures are value types and are always copied when they are passed around in your code, and classes are reference type and are passed by reference. Also, classes have Inheritance which allows one class to inherit the characteristics of another. Struct properties are stored on Stack and Class instances are stored on Heap hence, sometimes the stack is drastically faster than a class. Struct gets a default initializer automatically whereas in Class, we have to initialize. Struct is thread safe or singleton at any point of time.

而且, 要总结结构和类之间的区别，有必要了解值类型和引用类型之间的区别。

在复制值类型时，它将从其中复制所有数据 你要复制到新变量中的东西。它们是分开的 事物和改变一个并不影响另一个。 复制引用类型时，新变量引用 与你要复制的东西相同的内存位置。这意味着 改变一个会改变另一个因为它们都指向 相同的内存位置。 下面的示例代码可以作为参考。

/ / sampleplayground.playground

  class MyClass {
        var myName: String
        init(myName: String){
            self.myName = myName;
        }
    }

    var myClassExistingName = MyClass(myName: "DILIP")
    var myClassNewName = myClassExistingName
    myClassNewName.myName = "John"


    print("Current Name: ",myClassExistingName.myName)
    print("Modified Name", myClassNewName.myName)

    print("*************************")

    struct myStruct {
        var programmeType: String
        init(programmeType: String){
            self.programmeType = programmeType
        }
    }

    var myStructExistingValue = myStruct(programmeType: "Animation")
    var myStructNewValue = myStructExistingValue
    myStructNewValue.programmeType = "Thriller"

    print("myStructExistingValue: ", myStructExistingValue.programmeType)
    print("myStructNewValue: ", myStructNewValue.programmeType)

输出:

Current Name:  John
Modified Name John
*************************
myStructExistingValue:  Animation
myStructNewValue:  Thriller

下面是一个例子，它精确地显示了struct和class之间的区别。

在操场上写的代码的截图

struct Radio1{
    var name:String
    //    init(name:String) {
    //        self.name = name
    //    }
}

struct Car1{
    var radio:Radio1?
    var model:String

}

var i1 = Car1(radio: Radio1(name:"murphy"),model:"sedan")
var i2 = i1
//since car instance i1 is a struct and 
//this car has every member as struct ,
//all values are copied into i2

i2.radio?.name //murphy
i2.radio = Radio1(name: "alpha")
i2.radio?.name //alpha

i1.radio?.name //murphy

//since Radio1 was struct , 
//values were copied and thus
// changing name  of instance of Radio1 in i2 
//did not bring change in i1

class Radio2{
    var name:String
    init(name:String) {
        self.name = name
    }
}

struct Car2{
    var radio:Radio2?
    var model:String

}
var i3 = Car2(radio: Radio2(name:"murphy"),model:"sedan")
//var radioInstance = Radio2(name: "murphy")
//var i3 = Car2(radio: radioInstance,model:"sedan")

var i4 = i3
//since i3 is instance of struct
//everything is copied to i4 including reference of instance of Radio2
//because Radio2 is a class



i4.radio?.name //murphy
i4.radio?.name="alpha"
i4.radio?.name //alpha

i3.radio?.name //alpha

//since Radio2 was class, 
//reference was copied and 
//thus changing name of instance 
//of Radio2 in i4 did  bring change in i3 too


//i4.radio?.name
//i4.radio = Radio2(name: "alpha")
//i4.radio?.name
//
//i3.radio?.name

类和结构都可以做到:

定义属性来存储值 定义提供功能的方法 被扩展 遵守协议 定义初始化 定义下标以提供对其变量的访问

唯一的类可以做到:

继承 铸字 定义deinitialisers 允许多个引用进行引用计数。

这个问题似乎是重复的，但无论如何，下面的问题将回答大多数用例:

One of the most important differences between structures and classes is that structures are value types and are always copied when they are passed around in your code, and classes are reference type and are passed by reference. Also, classes have Inheritance which allows one class to inherit the characteristics of another. Struct properties are stored on Stack and Class instances are stored on Heap hence, sometimes the stack is drastically faster than a class. Struct gets a default initializer automatically whereas in Class, we have to initialize. Struct is thread safe or singleton at any point of time.

而且, 要总结结构和类之间的区别，有必要了解值类型和引用类型之间的区别。

在复制值类型时，它将从其中复制所有数据 你要复制到新变量中的东西。它们是分开的 事物和改变一个并不影响另一个。 复制引用类型时，新变量引用 与你要复制的东西相同的内存位置。这意味着 改变一个会改变另一个因为它们都指向 相同的内存位置。 下面的示例代码可以作为参考。

/ / sampleplayground.playground

  class MyClass {
        var myName: String
        init(myName: String){
            self.myName = myName;
        }
    }

    var myClassExistingName = MyClass(myName: "DILIP")
    var myClassNewName = myClassExistingName
    myClassNewName.myName = "John"


    print("Current Name: ",myClassExistingName.myName)
    print("Modified Name", myClassNewName.myName)

    print("*************************")

    struct myStruct {
        var programmeType: String
        init(programmeType: String){
            self.programmeType = programmeType
        }
    }

    var myStructExistingValue = myStruct(programmeType: "Animation")
    var myStructNewValue = myStructExistingValue
    myStructNewValue.programmeType = "Thriller"

    print("myStructExistingValue: ", myStructExistingValue.programmeType)
    print("myStructNewValue: ", myStructNewValue.programmeType)

输出:

Current Name:  John
Modified Name John
*************************
myStructExistingValue:  Animation
myStructNewValue:  Thriller

已经有很多关于这方面的文章了，我想在这里加一个类比。希望你看完这篇文章后，心中永远不会再有疑虑: 底线: 类通过引用传递，而结构通过值传递。

假设你和你的朋友共享一个谷歌文档表。现在，如果他改变了其中的任何内容，你也会在谷歌文档上看到变化，这意味着你的副本也受到了影响。 这基本上是“通过引用传递”。

但假设，如果你有一个。xls文件保存在你的机器。你把那份文件交给你的朋友。现在，如果他在那个文件中做了任何更改，你的文件也不会被打乱/影响，因为你有自己的副本。 这基本上就是“按值传递”。 你有多个简单的程序已经在那里检查这个类比在快速操场。

以上答案都是正确的，我希望我的回答能帮助到那些不理解以上答案的人。

在Swift中有两种类型的对象

结构体 类

它们之间的主要区别是

Struct是值类型 类是引用类型

例如这里的代码要理解得很好。

struct SomeStruct {
var a : Int;

init(_ a : Int) {
    self.a = a
}
}

class SomeClass {
var a: Int;

init(_ a: Int) {
    self.a = a
}

}
var x = 11

var someStruct1 = SomeStruct(x)
var someClass1 = SomeClass(x)

var someStruct2 = someStruct1
var someClass2 = someClass1

someClass1.a = 12
someClass2.a // answer is 12 because it is referencing to class 1     property a

someStruct1.a = 14
someStruct2.a // answer is 11 because it is just copying it not referencing it

这是主要的区别，但我们也有次要的区别。

类

必须声明初始化式(构造函数) 有deinitialisers 可以从其他类继承吗

结构体

它为你提供了自由初始化器，你不必声明初始化器，如果你声明了自由初始化器，它将被你声明的初始化器覆盖 没有去初始化 不能从其他结构继承