swift 练习三

//: Playground - noun: a place where people can play
class YOU{}

class MyClass {

    var arr:Array = ["1","2"]

    //延迟实例化
    lazy var obj = YOU()

    var prop:String = "hello"

    func mymethod(){
        print("no")
    }

    //类属性
    static var CP:String = "类型属性"

    //类方法
    class func cf(){

    }

    //属性监视器
    var total:Int = 0{

        willSet(newValues){
            print(newValues)
        }

        didSet{
            print(oldValue)
        }
    }

}

protocol  MyProtocol{

    func say(word:String)

}

extension MyClass:MyProtocol{

    func test(){
        print(self.prop)
    }

    func say(word: String) {
        print(word)
    }

    //类只能扩展计算属性,要返回点什么
    var calc:String{
        get{
            return self.prop + ",world"
        }

        set{
           self.calc =  newValue + "888"
        }
    }


//    func getInstance(){
//        return self
//    }

//    convenience init(){
//    
//    }


    enum K{
      case  A,B,C
    }


    subscript (outindex:Int)->String{
        return self.arr[outindex]
    }
}


MyClass.CP

MyClass.cf()

var my = MyClass()

my.test()

my.calc = "666"

print(my.calc)

print(my[0])

MyClass.K.A