swift的类与对象讲解

• 最简答的类和对象

import UIKit

class Shape{

    var numberOfSides=0;

    func ReturnDescription() ->String{

        return"it has \(numberOfSides) sides";

    }

}

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.

        var MyShape=Shape();

        MyShape.numberOfSides=3;

        var StringFromClass=MyShape.ReturnDescription();

        println("\(StringFromClass)");

        

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

}

但是一般都需要有构造器，需要加init方法

import UIKit

class ShapeWithInit{

    var numberOfSide:Int;//类的属性

    init(numberOfSideGet:Int){//必须得与上面的变量名字不同

        numberOfSide=numberOfSideGet;

    }

    func GetSimpleDesciption(name:String)->String{

        return"hello,\(name),it has\(numberOfSide) sides"

    }

}

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.

        var myShape=ShapeWithInit(numberOfSideGet:3);//必须的加参数，而且前面必须加构造函数的参数名称，不是属性的名称

        var stringGet=myShape.GetSimpleDesciption("wtt");

        println(stringGet);

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

}

下面在讲下类的继承。下面的代码包括的方法的重写，每一步都有特定的意义在，需要仔细看。

import UIKit

class ShapeWithInit{

    var numberOfSide:Int;//类的属性

    var shapeAdditional:String;//类的属性

    init(numberOfSideFromObject:Int){//必须得与上面的变量名字不同，构造对象的时候需要传参进来。但是不一定所有的属性都需要传进来。

        numberOfSide=22;//所有的属性必须在这里被初始化，但是不一定用传进来的参数。额，当然不建议这样做

        shapeAdditional="this is class ShapeWhithInit";

    }

    func GetSimpleDesciption(name:String)->String{

        return"hello,\(name),\(shapeAdditional),it has\(numberOfSide) sides"

    }

}

class Squre:ShapeWithInit{

    var lengthOfClass:Double;

    init(lengthFromSqureObject:Double,number:Int){//子类的构造方法中，参数多了长度

        self.lengthOfClass=lengthFromSqureObject;

        super.init(numberOfSideFromObject: number);//父类的构造方法

        numberOfSide=4;

    }

   override func  GetSimpleDesciption(name: String) ->String {//如果需要重写父l类的方法需要在前面加上override关键字

        return"hello,it is from fulei,additional,\(shapeAdditional).it is from zilei ,lengthofclass,\(lengthOfClass),numberofside,\(numberOfSide)";

    }

}

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.

       

        var mySqure=Squre(lengthFromSqureObject:12.5,number:4);

        var stringGet=mySqure.GetSimpleDesciption("wtt");

        println(stringGet);

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

}