swift - 在 Swift 中，从 init() 调用时 didSet 不会触发

Question

我有车和司机。他们相互引用。在汽车的 init() 中，我创建了一个驱动程序并将其分配给驱动程序成员。 driver 成员有一个 didSet 方法，该方法应该设置司机的车，从而将它们相互链接起来。

class GmDriver {
    var car: GmCar! = nil
}

class GmCar {
    var driver: GmDriver {
        didSet {
            driver.car = self
        }
    }
    init() {
        driver = GmDriver()
    }
}

let myCar = GmCar()
println(myCar.driver.car) // nil

但是，didSet 永远不会触发。为什么？

Answer 1

Apple Documentation :

The willSet and didSet observers of superclass properties are called when a property is set in a subclass initializer, after the superclass initializer has been called. They are not called while a class is setting its own properties, before the superclass initializer has been called.