有时觉得SWIFT的语法真的强大而又变态，不说了，直接上代码瞅瞅：
首先先定义一个交通工具的父类
class Vehicle{
var wheels:Int!
var speed:Double!
init(wheels:Int,speed:Double){
self.speed = speed
self.wheels = wheels
}
func run(){
println("The (self.wheels) wheels is running as (self.speed) speed")
}
deinit{//类似于其它编程语言的析构函数，退出时释放对象
self.wheels = nil
self.speed = nil
}
}
创建一个自行车类
class Bike : Vehicle{
init(){
super.init(wheels: 2, speed: 10)
}
}
创建一个小车类及一个加油的方法
class Car : Vehicle{
init(){
super.init(wheels: 4, speed: 100.5)
}
func addOil(){
println("The Car is adding oil")
}
}
创建一个货车类及添加货物的方法
class Truck : Vehicle{
init(){
super.init(wheels: 4, speed:80.5)
}
func addCargo(){
println("The Car is adding cargo")
}
}
var myvehicle:Vehicle = Car()
判断如果是小车类型的
if (myvehicle is Car){
println("This is a car")
}
switch myvehicle{
case let bike as Bike: //此时，如果myvehicle是Bike对象那边将myvehicle赋值给bike变量。下面的代码也类似
bike.run()
case let car as Car where car.speed == 100.5: //如果是Car并且速度是100.5，这语法真的很变态
car.addOil() //调用自有方法
car.run()
case let truck as Truck:
truck.addCargo()//调用自有方法
default:
println("unknow")
}