class vs struct

Class

• class is reference type.
• class object is created on Heap memory.
• For class member variable can initialised directly.
• class have constructor and destructor methods of all types.
• class can inherit another class.
• class are good for larger or complex object.

Struct

• struct is value type.
• struct object is created on Stack memory.
• For struct member vaiable can not initialised directly.
• struct can't be abstract.
• stucts are good for small and isolated model object.  

Example of class

- created one Student class with name and lname property with init method

class Student{

    var name : String?

    var lname : String?

    init(name : String?,lname : String?) {

        self.name = name

        self.lname = lname

    }

}

- now create one object for Student class called objStudent and print

let objStudent = Student(name: "Pratik", lname: "Lad")

dump(objStudent)

Output :

__lldb_expr_44.Student #0

  ▿ name: Optional("Pratik")

    - some: "Pratik"

  ▿ lname: Optional("Lad")

    - some: "Lad"

- now one more object create and assign older object of Student class

let obj1Student = objStudent

- now change the name of obj1Student object

obj1Student.name = "Bunty"

- now print both object 

dump(objStudent)

Output :

__lldb_expr_44.Student #0

  ▿ name: Optional("Bunty")

    - some: "Bunty"

  ▿ lname: Optional("Lad")

    - some: "Lad"

dump(obj1Student)

Output :

__lldb_expr_44.Student #0

  ▿ name: Optional("Bunty")

    - some: "Bunty"

  ▿ lname: Optional("Lad")

    - some: "Lad"

you can see the objStudent object name also change because class is reference type.

Example of struct

- created one Student struct with name and lname property with init method

struct Student{

    var name : String?

    var lname : String?

    init(name : String?,lname : String?) {

        self.name = name

        self.lname = lname

    }

}

- now create one object for Student struct called objStudent and print

let objStudent = Student(name: "Pratik", lname: "Lad")

dump(objStudent)

Output :

__lldb_expr_44.Student #0

  ▿ name: Optional("Pratik")

    - some: "Pratik"

  ▿ lname: Optional("Lad")

    - some: "Lad"

- now one more object create and assign older object of Student struct

var obj1Student = objStudent

- now change the name of obj1Student object

obj1Student.name = "Bunty"

- now print both object 

dump(objStudent)

Output :

__lldb_expr_44.Student #0

  ▿ name: Optional("Pratik")

    - some: "Bunty"

  ▿ lname: Optional("Lad")

    - some: "Lad"

dump(obj1Student)

Output :

__lldb_expr_44.Student #0

  ▿ name: Optional("Bunty")

    - some: "Bunty"

  ▿ lname: Optional("Lad")

    - some: "Lad"

you can see the objStudent and obj1Student object name not change because struct is value type.

Thanks for reading this article.