Swift继承

//声明一个基类

class vehicle {

var maxPassenger :
Int =
0

var manufacturer :
String!

func description() ->
String {

return
"max passenger is \(maxPassenger) and manufacturer is
\(manufacturer)"

}

init () {

maxPassenger =
2

manufacturer =
"Designed By Weasley"

}

}

//声明子类

class Bicycle :
vehicle {

var numberofWheels :
Int =
2

var maxSpeed :
Double = 30

override
init() {

super.init()

maxPassenger =
2

}

override
func description() ->
String {

//return "numberofWheels : \(numberofWheels) maxPassenger : \(maxPassenger) with maxSpeed : \(maxSpeed) manufacturer is \(manufacturer)"

return
super.description() +
";" + "numberofWheels :
\(numberofWheels) maxSpeed :
\(maxSpeed)"

}

}

class LimitSpeedBicycle:
Bicycle {

override
var maxSpeed : Double {

get {

return
super.maxSpeed

}

set {

super.maxSpeed =
min(maxSpeed,
20)

}

}

}

var bicycle =
Bicycle()

println(bicycle.description())

var limit =
LimitSpeedBicycle()

limit.maxSpeed =
30

println(limit.maxSpeed)

class SpeedLevel:
Bicycle {

var level  =
1

override
var maxSpeed : Double{

didSet{

level = Int(maxSpeed /
10) +
1

}

}

override
func description() ->
String {

return
super.description() +
" level is \(level)"

}

}

var aBicycle =
SpeedLevel()

aBicycle.maxSpeed =
40

println(aBicycle.description())