tranhieutt

//Declare class
class Cat {
    var name: String
    init(name: String) {
        self.name = name
    }
}

class Dog {
    var name:String

tranhieutt

extension Cat: Pet {}
extension Dog: Pet {}
let pets: [Pet] = [Cat(name: "Mistten"), Dog(name: "Yeeker")]

tranhieutt

func herd<Animal: Cat> (_ cats: [Animal]) {
    cats.forEach {
        print("Here,cat,  \($0.name)! come here")
    }
}
func herd<Animal: Dog> (_ dogs: [Animal]) {
    dogs.forEach {
        print("Here, dog, \($0.name)! come here")
    }
}

tranhieutt

class Handler {
    func handle() {
        let data = requestDataToAPI()
        let array = parse(data: data)
        saveToDB(array:array)
    }
    
    private func requestDataToAPI() -> Data {
        //send API request and wait the response
    }

tranhieutt

class Handler {
    let apiHandler: APIHandler
    let parseHandler: ParseHandler
    let dbHandler: DBHandler
    
    init(apiHandler: APIHandler, parseHandler:parseHandler, dbHandler:DBHandler) {
        self.apiHandler = apiHandler
        self.parseHandler = parseHandler
        self.dbHandler = dbHandler
    }

tranhieutt

class Logger {
    func printData() {
        let cars = [
            Car(name: "BWM", color: "Green"),
            Car(name: "Toyota", color: "Blue"),
            Car(name: "Honda", color: "Black")
        ]
    
    cars.forEach { cars in
        print(car.printDetails())

tranhieutt

class Logger {
    func printData() {
        let cars = [
            Car(name: "BWM", color: "Green"),
            Car(name: "Toyota", color: "Blue"),
            Car(name: "Honda", color: "Black")
        ]
  
        cars.forEach {cars in
            print(cars.printDetails())

tranhieutt

//SOLID - O 
protocol Printable {
    func printDetails() -> String
}
class Logger {
    func printData() {
        let vehices: [Printable] = [
            Car(name: "BWM", color: "Green"),
            Car(name: "Toyota", color: "Blue"),
            Car(name: "Honda", color: "Black"),

tranhieutt

 //Not preferred:
class MyViewController: UIViewController, UITableViewDataSource, UIScrollViewDelegate {
  // all methods
}
//Preferred:
class MyViewController: UIViewController {
  // class stuff here
}

// MARK: - UITableViewDataSource

tranhieutt

//Preferred:
if user.isHappy {
  // Do something
} else {
  // Do something else
}

//Not Preferred:
if user.isHappy
{