Swift Learning-Definition of class, use, inheritance, construction, etc. (v)

Swift Learning -- the definition of class, used. inheritance, construction, etc. (v.)

Instructions for using the class

1 using class and class names to create a class name, such as: class student

The only difference between the declaration of a property in class 2 and a constant and a variable is that their context is a class

3 methods and function declarations are the same

// 1 ---- simple class introduction
class Student {
    
    // The variable student number is initialized to 0
    var num = 0;
    
    // member function
    func GetNum ()-> Int {
        return num
    }
}

// Create an instance of the class

var student = Student ()


// Access the member variables of the class

student.num = 1

// Access member functions of the class
var Num = student.GetNum ()

// Print out class variables and member functions
println ("student1 num is \ (student.num)")
println ("student2 num is \ (Num)")


// 2 ---- Constructors and destructors in the class

/ *
    Constructor init
    Destructor deinit
* /

class StudentLow {
    var numberlow: Int = 0
    var namelow: String
    
    //Constructor. Constructor to assign
    init (namelow: String) {
        
        / *
            self is used to distinguish instance variables. When you create an instance, you give the class the same as a function parameter
            The parameters passed to the constructor.
Every property needs to be assigned a value-whether through numberlow
            Still through the constructor (like namelow)
        * /
        
        self.namelow = namelow
    }
    
    func simpleDescription ()-> String {
        
        return "I am is low studnet"
    }
    
}

// Note that my constructor has parameters, here I create the instance object. The parameters are correct

var studentlow1 = StudentLow (namelow: "Jhon")

studentlow1.numberlow = 2

println ("studentlow1 num is \ (studentlow1.numberlow)")
println ("studentlow1 name is \ (studentlow1.namelow)")
println ("studentlow1 information is \ (studentlow1.simpleDescription ())")


// 3 ---- inherit class. Create a subclass of StudentLow

/ *
    Inheritance note:
        Subclasses are defined by appending the name of the parent class to their class name and cutting them with a colon.
        Creating a class does not require a standard root class, so you can ignore the parent class.
* /

class StudentHight: StudentLow {
    
    var grade: Double
    
    init (grade: Double, name: String) {
        self.grade = grade
        
        // Note that the namelow: name parameter is passed
        
        super.init (namelow: name)
        numberlow = 3
    }
    
    func Grade ()-> Double {
        return grade * 0.9
    }
    
    // If the subclass assumes that you want to override the method of the parent class, you need to use the override tag-assuming that the override of the parent method without adding override, the compiler will report an error.
    // The compiler will also check if the method marked by override is indeed in the parent class.
    
    override func simpleDescription ()-> String {
        return "I am a hight student"
    }
    
}

// Create an instance object

let studenthight1 = StudentHight (grade: 98, name: "lucy")

println ("studenthight1 num is \ (studenthight1.numberlow)")

println ("studenthight1 name is \ (studenthight1.namelow)")

//call function
println ("Greades is \ (studenthight1.Grade ())")

println ("studenthight1 grade is \ (studenthight1.grade)")

//call function
println ("studenthight1 information is \ (studenthight1.simpleDescription ())");



Swift learning-class definition, use, inheritance, construction, etc. (5)