A Swift-y Approach to Dependency Injection

SwiftDI.swift

// Refer to: https://danielhall.io/a-swift-y-approach-to-dependency-injection
// Part two: https://www.danielhall.io/swift-y-dependency-injection-part-two

import Foundation

protocol NetworkingInjected {}

extension NetworkingInjected {
  var networking: NetworkingProtocol {
    return NetworkInjector.injectNetworking()
  }
}

protocol NetworkingProtocol {
  func request()
}

class MyNetworkingManager: NetworkingProtocol {
  func request() {
    
  }
}

class HisNetworkingManager: NetworkingProtocol {
  func request() {
    
  }
}

struct NetworkInjector {
  static func injectNetworking() -> NetworkingProtocol {
    return MyNetworkingManager() // default
  }
  
  static func injectTestingNetworking() -> NetworkingProtocol {
    return HisNetworkingManager()
  }
  
  // Method 1: Using property. Can set to different value during test later
//  static var networking: NetworkingProtocol {
//    return MyNetworkingManager() // default
//  }
}

class MyViewModel: NetworkingInjected {
  func getData() {
    networking.request()
  }
}

class TestCase: NetworkingInjected {
  var networking: NetworkingProtocol {
    return NetworkInjector.injectTestingNetworking()
  }
  
  func startTest() {
    networking.request()
  }
}