Why I can not inherit from multiple classes in swift just like it's library classes

Question

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

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

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'     } } 

Answer 1

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

class SecondViewController: UIViewController, UITextFieldDelegate 

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