Detailed analysis of different architectures

Article directory

Detailed analysis of different architectures

Traditional MVC architecture

**The traditional MVC architecture divides the system into three parts: model (Model), view (View) and controller (Controller). **The model represents data and data processing logic; the view represents the user interface; the controller receives user input and handles real actions. The advantage of this architecture is that it is simple and easy to understand, easy to develop and maintain; the disadvantage is that when the application scale becomes larger, there will be problems with bloated controllers and mixed business logic, which is not conducive to code reuse and maintenance.

MVVM architecture

**MVVM architecture divides the system into three parts: view (View), view model (ViewModel) and model (Model). ** The view is responsible for rendering and user input; the view model handles the logic and updates the view; the model is related to the data. Through the data binding mechanism, the view model can directly reflect changes to the view, thus achieving the characteristics of low coupling and high reusability. The disadvantage is that the implementation is complicated, two-way data binding needs to be realized, and the amount of code is relatively large.

VIPER Architecture

** The VIPER architecture divides the system into five parts: View, Presenter, Interactor, Entity, and Router. **The presenter is responsible for parsing the user's operation into an executable operation of the interactor; the interactor is responsible for executing specific business logic and returning the result to the presenter; the entity stores the actual business logic, and the routing is responsible for the routing and navigation between modules. The architecture implements the Single Responsibility Principle (SRP), has high code reusability, and is easy to maintain. The disadvantage is that the layering is too detailed, the amount of code is slightly larger, and it is difficult to get started.

Clean Swift (also known as VIP) architecture

** Clean Swift divides the system into six parts: View Controller (ViewController), Presenter (Presenter), Business Logic Processor (Interactor), Entity (Entity), Request (Request) and Response (Response). **Clean Swift is in principle a variant of VIPER. The architecture advocates the Single Responsibility Principle (SRP), achieves the goal of separation of duties, and ensures the testability and maintainability of the code. In Clean Swift, the view controller is only responsible for managing the life cycle of the interface and the processing of UI events, while the actual business logic and data processing are placed in components such as presenters, business logic processors, and entities. The advantage of this architecture is that the responsibilities are clearly layered, the code is concise and readable, and it is easy to read and maintain; at the same time, it provides a unified request, response and error handling interface, which is conducive to improving code reusability and testability. The disadvantage is that you need to follow the conventional programming specification.

demo

The following is a demo of a simple To-do List application written using the Clean Swift architecture, which includes functions such as adding, viewing, editing, and deleting to-do items.

1. Create an Xcode project

Open Xcode.
Create a new iOS App project and name it ToDoListDemo.
SwiftSelect Language and User Interface in the project settings Storyboard.

2. Create schema files and classes

In Xcode, create several Groups to store various parts of the Clean Swift architecture, such as: Models, Networking, and Sceneso on.

In Scenethe Group, create a new Swift file named ToDoListModels.swift. In this file define all necessary types, structures and models used in the application.

// 创建 TodoItem 结构体
struct TodoItem {
      
      
    var id: Int
    var title: String
    var description: String?
    var isCompleted: Bool
    var date: Date?
}

// 创建 TodoListViewModel 结构体
struct TodoListViewModel {
      
      
    var items: [TodoItem]
}

In Scenethe Group, create a new Swift file named ToDoListWorker.swift. This file will contain code that performs network requests and data persistence.

protocol TodoListWorkerProtocol {
      
      
    func fetchItems(completion: ([TodoItem]) -> Void)
    func saveItem(_ item: TodoItem, completion: @escaping (Bool) -> Void)
    func deleteItem(_ item: TodoItem, completion: @escaping (Bool) -> Void)
}

class TodoListWorker: TodoListWorkerProtocol {
      
      

    func fetchItems(completion: ([TodoItem]) -> Void) {
      
      
        // 在此处执行网络请求或者数据持久化操作
        // 返回获取到的 TodoItem 数据
    }

    func saveItem(_ item: TodoItem, completion: @escaping (Bool) -> Void) {
      
      
        // 在此处执行网络请求或者数据持久化操作
        completion(true)
    }

    func deleteItem(_ item: TodoItem, completion: @escaping (Bool) -> Void) {
      
      
        // 在此处执行网络请求或者数据持久化操作
        completion(true)
    }
}

In Scenethe Group, create a new Swift file named ToDoListInteractor.swift. In this file create the interface TodoItemfor the operation TodoListInteractorand provide TodoListInteractora default implementation for the .

protocol TodoListInteractorProtocol {
      
      
    func fetchTodoList()
    func addTodoItem(item: TodoItem)
    // 添加更新和删除操作方法
}

class TodoListInteractor: TodoListInteractorProtocol {
      
      
    
    var presenter: TodoListPresenterProtocol?
    var worker: TodoListWorkerProtocol?
    
    func fetchTodoList() {
      
      
        worker?.fetchItems(completion: {
      
       [weak self] items in
            self?.presenter?.presentFetchedTodoList(response: items)
        })
    }

    func addTodoItem(item: TodoItem) {
      
      
        worker?.saveItem(item, completion: {
      
       [weak self] success in
            if success {
      
      
                self?.fetchTodoList()
            }
        })
    }
    
    // 添加更新和删除操作方法的默认实现
}

In Scenethe Group, create a new Swift file named ToDoListPresenter.swift. In this file, create an interface that represents the obtained and the TodoItemmanipulated , and provide a default implementation of .TodoListViewModelTodoListPresenterTodoListPresenter

protocol TodoListPresenterProtocol {
      
      
    func presentFetchedTodoList(response: [TodoItem])
    // 添加更新和删除操作方法
}

class TodoListPresenter: TodoListPresenterProtocol {
      
      
    
    weak var viewController: TodoListViewControllerProtocol?

    func presentFetchedTodoList(response: [TodoItem]) {
      
      
        let viewModel = TodoListViewModel(items: response)
        viewController?.displayFetchedTodoList(viewModel: viewModel)
    }

    // 添加更新和删除操作方法的默认实现
}

In Scenethe Group, create a new Swift file named ToDoListViewController.swift. In this file, create the interfaces that represent the user interface TodoListViewControllerand that represent user input TodoListViewControllerInput, and provide TodoListViewControllerdefault implementations for .

protocol TodoListViewControllerProtocol: AnyObject {
      
      
    func displayFetchedTodoList(viewModel: TodoListViewModel)
}

protocol TodoListViewControllerInput {
      
      
    func displayAddTodoItemSuccess()
    // 添加更新和删除操作方法
}

class TodoListViewController: UIViewController, TodoListViewControllerProtocol {
      
      
    
    var interactor: TodoListInteractorProtocol?
    var router: TodoListRouterProtocol?

    // 实现 viewDidLoad() 和其他方法

    func displayFetchedTodoList(viewModel: TodoListViewModel) {
      
      
        // 更新用户界面以显示获取到的数据
    }
    
    // 添加更新和删除操作的默认实现
}

In Scenethe Group, create a new Swift file named ToDoListRouter.swift. In this file create TodoListRouterthe interface that represents the navigation logic and provide TodoListRoutera default implementation of the .

protocol TodoListRouterProtocol {
      
      
    func navigateToAddTodoItem()
    // 添加其他导航方法
}

class TodoListRouter: TodoListRouterProtocol {
      
      
    
    weak var viewController: UIViewController?
    
    // 实现 TodoListRouterProtocol 中的方法
    // 可以使用 NavigationController 或 Modal 方式实现不同的导航
}

3. Generate the view controller and complete the basic logic

Create a new UIViewControllerclass in Xcode, name it ToDoListTableViewController, and set it as the splash screen in the storyboard.
Use Interface Builder to create the displayed TodoItemlist and lay it out and design it accordingly.

NOTE: Only part of the code is included in this section. The full code can be found in my GitHub repository: https://github.com/techsleep/clean-swift-todo-app-demo.

In ToDoListTableViewController.swiftthe file, declare and initialize interactor, presenterand router.

class ToDoListTableViewController: UITableViewController {
      
      
    
    var interactor: TodoListInteractorProtocol?
    var presenter: TodoListPresenterProtocol?
    var router: TodoListRouterProtocol?
    
    override func viewDidLoad() {
      
      
        super.viewDidLoad()
        interactor = TodoListInteractor()
        interactor?.presenter = presenter
        presenter = TodoListPresenter()
        presenter?.viewController = self
        router = TodoListRouter()
        router?.viewController = self
        interactor?.fetchTodoList()
        // 设置 NavigationController 样式和导航按钮等
    }
}

In ToDoListTableViewController.swiftthe file, follow TodoListViewControllerInputthe protocol and add the action methods needed to implement it.

extension ToDoListTableViewController: TodoListViewControllerInput {
      
      

    func displayAddTodoItemSuccess() {
      
      
        // 在该回调中处理添加待办事项成功后的操作
    }

    // 添加更新和删除待办事项操作方法
}

In ToDoListTableViewController.swiftthe file, implement methods that are called when the user enters an action, such as adding a to-do or navigating to the add page, etc.

class ToDoListTableViewController: UITableViewController {
      
      

    @IBAction func addButtonClicked(_ sender: Any) {
      
      
        router?.navigateToAddTodoItem()
    }
    
    // 添加其他用户输入操作方法
}

In TodoListRouter.swiftthe file, implement the specific logic of the navigation page.

class TodoListRouter: TodoListRouterProtocol {
      
      
    
    weak var viewController: UIViewController?
    
    func navigateToAddTodoItem() {
      
      
        let addTodoItemVC = storyboard.instantiateViewController(withIdentifier: "AddTodoItemViewControllerID") as! AddTodoItemViewController
        addTodoItemVC.delegate = viewController as? AddTodoItemViewControllerDelegate
        viewController?.navigationController?.pushViewController(addTodoItemVC, animated: true)
    }
    
    // 添加其他导航
}

4. Complete the rest of the logic

In AddTodoItemViewController, define AddTodoItemViewControllerDelegateand TodoItemobjects, and notify via the protocol that TodoListViewControllera new todo has been added.
In AddTodoItemViewController, use TodoListWorkerthe object to store new to-do items, and then notify via the protocol that TodoListInteractorthe data has been updated.
In TodoListInteractor, use TodoListPresenterthe object to update the UI to show the new todo.

After completing the above operations, you can use the demo of the To-do List application written in the Clean Swift framework to run normally!