var name:String{
    get{
        return self.name
    }
}

//read/write Setters/Getters用来计算和获取属性，
//并没有给成员变量实例分配存储,所以，会触发EXC_BAD_ACCESS.
private var realAge:Int = 0;

var age:Int{
    get{
        return realAge
    }

    set{
        realAge = newValue
    }
}

 @property(nonatomic, retain)NSString address;

private var _address :String = ""{
    willSet{

          println("old Value = \(_address) will clear,new value = \(newValue) will set")

        self._address = newValue;
    }
    didSet{
        //可以追回一些额外的处理逻辑
         println("Property did set")
    }
}

var address :String{
    get{
        return self._address;
    }
    set(newAddress){
        if newAddress != _address{
            self._address = newAddress
        }
    }
}

class QBaseClass{

    //read only
    var name:String{
        get{
            return self.name
        }
    }

    //read/write Setters/Getters用来计算和获取属性，
    //并没有给成员变量实例分配存储,所以，会触发EXC_BAD_ACCESS.
    private var realAge:Int = 0;

    var age:Int{
        get{
            return realAge
        }

        set{
            realAge = newValue
        }
    }

    //read/write  with backing store，
    //类似 @property(nonatomic, assign)NSInter number;变量自动为_number
    private var _number:UInt = 0;

    var number :UInt{
        get{
            return self._number;
        }
        set(newNumber){
            if newNumber != number{
                self._number = newNumber
            }
        }
    }

    //read/write  with backing store,信息隐藏，监控属性变化，附加额外处理
     //类似 @property(nonatomic, retain)NSString address;变量自动为_address
    private var _address :String = ""{
        willSet{

            println("old Value = \(_address) will clear,new value = \(newValue) will set")

            self._address = newValue;
        }
        didSet{
            //可以追回一些额外的处理逻辑
             println("Property did set")
        }
    }

    var address :String{
        get{
            return self._address;
        }
        set(newAddress){
            if newAddress != _address{
                self._address = newAddress
            }
        }
    }


    init(){
        self.age = 0;
    }

}

var baseClass:QBaseClass = QBaseClass()

//baseClass.name = "ksnowlv"//报错
baseClass.address = "北京海淀区"
baseClass.age = 20;
baseClass.number = 0917;
println("address =\(baseClass.address),age =\(baseClass.age),number =\(baseClass.number)")

old Value =  will clear,new value = 北京海淀区 will set
Property did set
address =北京海淀区,age =20,number =917