LeeKahSeng

let animalArray: [Animal] = [myTiger, myCow]
let foodArray: [Any] = [Meat(), Grass()]
for (animal, food) in zip(animalArray, foodArray) {
    // Feed the animal with their favorite food
    animal.eat(food: food)
}

LeeKahSeng

enum AnyAnimal: Animal {
    
    case cow(Cow)
    case tiger(Tiger)
    
    var name: String {
        switch self {
        case let .cow(animal):
            return animal.name
        case let .tiger(animal):

LeeKahSeng

// Create concrete type Animal
let myTiger = Tiger(withName: "My Tiger")
let myCow = Cow(withName: "My Cow")

// Instantiate AnyAnimal with concrete type Animal
let anyTiger = AnyAnimal.tiger(myTiger)
let anyCow = AnyAnimal.cow(myCow)

let animalArray: [AnyAnimal] = [anyTiger, anyCow]
let foodArray: [Any] = [Meat(), Grass()]

LeeKahSeng

protocol Animal {
    
    var name: String { get }
    func walk()
    
    associatedtype FoodType
    func eat(food: FoodType)
}

class Cow: Animal {

LeeKahSeng

struct AnyAnimal: Animal {
    
    let name: String
    private let walker: () -> Void
    private let eater: (Any) -> Void
    
    init<T: Animal>(_ animal: T) {
        name = animal.name
        
        walker = {

LeeKahSeng

import Foundation
import CoreData
import UIKit

@objc(TestEntity)
public class TestEntity: NSManagedObject {
    
    var image: UIImage {
        set {
            base64 = base64(from: image)

LeeKahSeng

import Foundation
import CoreData

extension TestEntity {

    @nonobjc public class func fetchRequest() -> NSFetchRequest<TestEntity> {
        return NSFetchRequest<TestEntity>(entityName: "TestEntity")
    }
}

LeeKahSeng

import Foundation
import CoreData
import UIKit

@objc(TestEntity)
public class TestEntity: NSManagedObject {
    
    @NSManaged private var base64: String
    var image: UIImage {
        set {

LeeKahSeng

class Bird {
    var name: String
    init(name: String) {
        self.name = name
    }
}

class Chicken: Bird {
    let canFly = false
}

LeeKahSeng

// Create another bird array that accept nil value
let otherBirds: [Bird?] = [chicken, nil]
let chicken4 = otherBirds[0] as? Chicken? // Cast successful: chicken4 type is Chicken??
let chicken5 = otherBirds[0] as! Chicken? // Cast successful: chicken5 type is Chicken?

let chicken6 = otherBirds[1] as? Chicken? // Cast failed: Trigger runtime error
let chicken7 = otherBirds[1] as! Chicken? // Cast failed: Trigger runtime error

let chicken8 = otherBirds[0] as? Chicken! // chicken8 type is Chicken?? | Warning: Using '!' here is deprecated and will be removed in a future release
let chicken9 = otherBirds[0] as! Chicken! // chicken9 type is Chicken? | Warning: Using '!' here is deprecated and will be removed in a future release