创建一个基类:Vehicle.Swift
import Foundation
//
// @brief 定义一个超类(车)
//
class Vehicle {
var numberOfWheels: Int
var maxPassengers: Int
// designated initializer
init() {
numberOfWheels = 0
maxPassengers = 2
println("call vehicle designated initializer")
self.nothingToDo()
}
func description() {
println("Vehicle has (\numberOfWheels) wheels and can hold \(maxPassengers) passengers at most")
}
// 使用@final防止被重写
@final func nothingToDo() {
println("call nothingToDo() and it is used @final to avoid overriding")
}
}
再创建一个子类Bicycle.swift:
import Foundation
//
// @brief 定义自行车类
//
class Bicycle : Vehicle {
// override property
override var numberOfWheels: Int {
get { // 重写属性,调用super.propertyName
println("overried property getter numberOfWheels")
return super.numberOfWheels
}
set {
println("overried property setter numberOfWheels")
super.numberOfWheels = max(newValue, 40)
}
}
// initializer 默认是不会被继承的
init() {
super.init() // initialize super class first
println("called designated initializer")
numberOfWheels = 2
}
// 重写方法
override func description() {
super.description()
println("func description() was called in Bicycle")
}
// // 不能重写
// override func nothingToDo() {
//
// }
}
在main.swift中测试:
import Foundation
let bicycle = Bicycle()
bicycle.numberOfWheels = 4
println(bicycle.numberOfWheels)
bicycle.maxPassengers = 84
println(bicycle.maxPassengers)
bicycle.description()
//测试结果数据
call vehicle designated initializer
call nothingToDo() and it is used @final to avoid overriding
called designated initializer
overried property setter numberOfWheels
overried property setter numberOfWheels
overried property getter numberOfWheels
40
84
Vehicle has (
umberOfWheels) wheels and can hold 84 passengers at most
func description() was called in Bicycle
Program ended with exit code: 0
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