Programming in Swift: Functions & Types

Jan 4 2022 · Swift 5.5, iOS 15, Xcode 13

Part 5: Protocols & Inheritance

42. Protocols

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Previous episode: 41. Challenge: Initializers Next episode: 43. Protocols & Extensions

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Notes: 42. Protocols

Update Notes: This course was originally recorded in 2019. It has been reviewed and all content and materials updated as of October 2021.

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So far, you’ve learned about three named types: enumerations, structures, and classes. There’s just one more to learn about: Protocols. You’ve already used protocols! CaseIterable was a protocol we used a few times on enumerations. And if you worked through Your First and Second SwiftUI app courses, you definitely used the “View” protocol.

32 class Animal {
//  let name: String
//
//  required init(name: String) {
//    self.name = name
//  }
//
//  func speak() { }
}

32 protocol Animal {

33 var name: String { get }

//  required init(name: String) {

class Dog: Animal {
43  let name: String
  var tricksLearnedCount: Int

class Cat: Animal {
61 let name: String
  
  override func speak() {

35 required init(name: String) {
    self.name = name
  }

//  func speak() { }

35   init(name: String)
//  required init(name: String) {

  var name: String { get }

  init(name: String)

//  func speak() { }

61 required init(name: String) {
    self.name = name
  }
  
  override func speak() {

45 self.tricksLearnedCount = tricksLearnedCount
    self.name = name
  }

37 func speak()

53 func speak() {

65 func speak() {

65 //  func speak() {
//    print("My name is \(name). Please leave me alone. I must look at this wall.")
//  }

65   func speak() {
    print("My name is \(name). Please leave me alone. I must look at this wall.")
  }

let animals: [Animal] = [Dog(name: "Fang"), Cat(name: "Mr. Midnight")]

77 Animal(name: "Animal")