MVVM with Swift P2

struct Category {
    let id: Int
    var name: String
}

import Foundation

protocol ICategoryService {
    func getCategoryById(id: Int) -> Category?
}

class CategoryService: ICategoryService {
    func getCategoryById(id: Int) -> Category? {
        let categories = [Category(id: 3, name: "Movies"),
                          Category(id: 4, name: "Books"),
                          Category(id: 5, name: "Computer")]
        
        let category = categories.filter({
            $0.id == id
        }).first
        
        return category
    }
}

import Foundation
import RxSwift

class HomeViewModel {
    var category: Category
    var service: ICategoryService
    
    var displayName: String {
        return transformName(category.name)
    }
    
    // 1
    var valueSubject: PublishSubject<String>
    
    init(category: Category, service: ICategoryService) {
        self.category = category
        self.service = service
        valueSubject = PublishSubject()
    }
    
    func transformName(_ name: String) -> String {
        let newName = name.enumerated().map { (index, character) -> String in
            if index % 2 == 0 {
                return character.uppercased()
            } else {
                return character.lowercased()
            }
        }
        
        return newName.joined()
    }
    
    // 2
    func getCategory(id: Int) {
        if let newCategory = service.getCategoryById(id: id) {
            self.category = newCategory
            valueSubject.onNext(transformName(category.name))
        }
    }
}

import UIKit
import RxSwift

class HomeView: UIViewController {
    @IBOutlet private weak var categoryNameLabel: UILabel!
    
    private var viewModel: HomeViewModel?
    private let disposeBag = DisposeBag()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let category = Category(id: 1, name: "Hollywood")
        viewModel = HomeViewModel(category: category, service: CategoryService())
        // 1
        self.categoryNameLabel.text = viewModel?.displayName
        
        // 2
        viewModel?.valueSubject
            .skip(1)
            .subscribeOn(MainScheduler.instance)
            .subscribe(onNext: { (displayName) in
                self.categoryNameLabel.text = displayName
            })
            .disposed(by: disposeBag)
    }
    
    @IBAction func didTapButtonChangeCategory(_ sender: Any) {
        // 3
        viewModel?.getCategory(id: 3)
    }
}