为什么我不能像库类一样从 swift 继承多个类 [英] Why I can not inherit from multiple classes in swift just like it's library classes

问题描述

我尝试通过从两个类继承来创建 myPet 但例如错误:

I try to create myPet by inherit from two classes but error for example:

import UIKit
class SecondViewController: UIViewController, UITextFieldDelegate {
    // No Error
}

然后定义以下类，然后创建新类 myPets，我喜欢继承 Dog 和 Substance.但是错误:来自类Dog"和Substance"的多重继承

Then the following classes were defined then create new class myPets which I like to inherit both Dog and Substance. But error: Multiple inheritance from classes 'Dog' and 'Substance'

class Dog:Animal {
    func sound()->String {
        return "Hong Hong"
    }
}

class Substance {
    func livingCompound()->String {
        return "Consist of bio-molecule"
    }
}

class myPets:Dog, Substance {
    func itsAddress()->String {
        // Error:Multiple inheritance from classes 'Dog' and 'Substance'
    }
}

推荐答案

Swift 不支持多重继承，在此遵循 Objective C.这不是继承自两个类:

Swift does not support multiple inheritance, following Objective C in this. This is NOT inheritance from two classes:

class SecondViewController: UIViewController, UITextFieldDelegate

继承自一类UIViewController，采用UITextFieldDelegate协议.在 https://developer.apple.com 上阅读协议/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Protocols.html

It is inheritance from one class UIViewController and adopting the UITextFieldDelegate protocol. Read about protocols at https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Protocols.html

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