//类
class Student: NSObject{
//存储属性:
var age :Int=0
var name:String?
var mathscore:Double=0.0
var chinesescore:Double=0.0
//计算属性; 平均成绩
var averageScroe:Double{
return(mathscore+chinesescore)/2;
}
//定义类属性：类属性是和整个类相关的属性，而且是通过类名进行访问的
static var courseCount:Int=0
}
//给类属性进行赋值
Student.courseCount=2;
//创建对象
let p=Student()
//对象属性赋值
p.age=10
p.name="哈哈"
p.mathscore=99.1
p.chinesescore=34.2
print(p.averageScroe)