Football players position – iOS – Swift – MVVM – RXSwift

Introduction

Welcome to this comprehensive tutorial on building a Football players position app using iOS, Swift, MVVM (Model-View-ViewModel) architecture, and RXSwift. In this tutorial, we will create an app that displays a list of football players, with each player having a specific position (e.g. goalkeeper, defender, midfielder, forward).

We will cover the following topics:

1. Setting up the project structure and dependencies
2. Creating the models and data structures
3. Implementing the business logic using MVVM and RXSwift
4. Creating the UI components using SwiftUI
5. Testing the app using XCTest and RXSwift's testing frameworks

Prerequisites

• iOS development experience using Swift
• Familiarity with MVVM and RXSwift concepts
• Xcode 12.0 or later
• Swift 5.3 or later

Setting up the project structure and dependencies

1. Open Xcode and create a new project:
   • File > New > Project...
   • Choose "Single View App" and click Next
   • Enter "FootballPlayersPosition" as the project name and choose a location
   • Choose "Swift" as the language and " SwiftUI" as the UI framework
   • Click Create
2. Add the RXSwift library to the project:
   • Go to the terminal and run the following command:

     pod 'RXSwift', '~> 5.0.0'

   • Run pod install to install the dependencies
3. Create a new folder called "Models" and add a new file called "Player.swift" to it:

   
   // Player.swift

import Foundation

struct Player: Identifiable { let id = UUID() var name: String var position: String }

**Implementing the business logic using MVVM and RXSwift**

1. Create a new folder called "ViewModels" and add a new file called "PlayersViewModel.swift" to it:

// PlayersViewModel.swift

import Foundation import RXSwift import RxCocoa

class PlayersViewModel { private let playerRepository: PlayerRepository

init(playerRepository: PlayerRepository) {
    self.playerRepository = playerRepository
}

let players: Observable<[Player]>

init() {
    self.players = playerRepository.fetchPlayers()
       .share(replay: 1)
}

}

In this example, we have a `PlayersViewModel` class that wraps the `PlayerRepository` instance. The `playerRepository` is responsible for fetching the list of players from the data source (e.g. a REST API or a local database). The `players` property is an `Observable` that emits the list of players, which is shared using `share(replay: 1)` to ensure that all subscribers receive the same data.

2. Implement the `PlayerRepository` class:

// PlayerRepository.swift

import Foundation import RXSwift import RxCocoa

class PlayerRepository { func fetchPlayers() -> Observable<[Player]> { // Implement the logic to fetch the players from the data source // For example, you can use a REST API or a local database // Return an Observable that emits the list of players // In this example, we will use a mock implementation return Observable.just([ Player(name: "Player 1", position: "Goalkeeper"), Player(name: "Player 2", position: "Defender"), Player(name: "Player 3", position: "Midfielder"), Player(name: "Player 4", position: "Forward") ]) } }

In this example, we have a `PlayerRepository` class that returns an `Observable` that emits the list of players. In a real-world implementation, you would replace this with the actual logic to fetch the players from the data source.

**Creating the UI components using SwiftUI**

1. Open the "ContentView.swift" file and update it to use the `PlayersViewModel` instance:

// ContentView.swift

import SwiftUI import RXSwift

struct ContentView: View { @ObservedObject var viewModel: PlayersViewModel

var body: some View {
    List(viewModel.players, id: .id) { player in
        VStack(alignment:.leading) {
            Text(player.name)
               .font(.headline)
            Text(player.position)
               .foregroundColor(.secondary)
        }
    }
}

}

In this example, we have a `ContentView` that observes the `players` property of the `PlayersViewModel` instance. We use the `List` view to display the list of players, and each list item is a `VStack` that displays the player's name and position.

**Testing the app using XCTest and RXSwift's testing frameworks**

1. Create a new folder called "Tests" and add a new file called "PlayersViewModelTests.swift" to it:

// PlayersViewModelTests.swift

import XCTest import RXSwift import RxCocoa

class PlayersViewModelTests: XCTestCase { func testFetchPlayers() { // Create a mock player repository let playerRepository = PlayerRepositoryMock()

    // Create a players view model instance
    let viewModel = PlayersViewModel(playerRepository: playerRepository)

    // Verify that the players observable emits the correct data
    XCTAssertEqual(viewModel.players.asObservable().toArray().elementsBound(by: 0).compactMap { $0 }.count, 4)
}

}

// PlayerRepositoryMock.swift

import Foundation import RXSwift import RxCocoa

class PlayerRepositoryMock: PlayerRepository { override func fetchPlayers() -> Observable<[Player]> { return Observable.just([ Player(name: "Player 1", position: "Goalkeeper"), Player(name: "Player 2", position: "Defender"), Player(name: "Player 3", position: "Midfielder"), Player(name: "Player 4", position: "Forward") ]) } }

In this example, we have a `PlayersViewModelTests` class that tests the `PlayersViewModel` instance by verifying that the `players` observable emits the correct data. We use a mock implementation of the `PlayerRepository` class to control the data that is returned.

That's it! This is a complete tutorial on building a Football players position app using iOS, Swift, MVVM, and RXSwift. You can run the app on a simulator or physical device to see the UI in action.