如何確定快速初始化程序中的自我類

Question

在父類的便利初始值設定項中，如何在調用self.init()之前確定當前類？

public class Vehicle { 

    public convenience init(withDictionary rawData: [String:AnyObject]) { 

     // how do I determine whether this is a Car here? 

     self.init() 

    } 

} 

public class Car: Vehicle { 

} 

public class Bike: Vehicle { 

} 

Answer 1

看起來像使用self.dynamicType被允許：

public class Vehicle { 

    public convenience init(withDictionary rawData: [String:AnyObject]) { 

     let myType = self.dynamicType 

     print("This is a \(myType)") 

     self.init() 

    } 

} 

public class Car: Vehicle { 

} 

public class Bike: Vehicle { 

} 

let car = Car(withDictionary: ["key":"value"]) 

// prints "This is a Car" 

Answer 2

你需要使用「是」運營商確定的那種類的。

public class Vehicle 
{ 

    public convenience init(withDictionary rawData: [String:AnyObject]) 
    { 

    self.init() 

    if self is Car 
    { 
     print("It's a car") 
    } 
    else if self is Bike 
    { 
     print("It's a bike") 
    } 

    } 
} 

但是，您也可以在汽車或自行車的初始化函數中進行初始化。