[Simple dependency manager] A simple dependency manager that cleans itself up completely because of using NSMapTable (https://swiftrocks.com/weak-dictionary-values-in-swift)

SimpleDependencyManager.swift

import Foundation
      
      final class DependencyStore {
      
          var factories = [String: () -> Dependency]()
      
          var cachedDependencies = NSMapTable<NSString, AnyObject>.init(
              keyOptions: .copyIn,
              valueOptions: .weakMemory
          )
      
          func register<T: Dependency>(dependencyFactory: @escaping () -> T) {
              let key = T.identifier
              factories[key] = dependencyFactory
          }
      
          func getInstanceOf<T: Dependency>(dependencyType type: T.Type) -> T? {
              let key = T.identifier
              let cachedInstance = cachedDependencies.object(forKey: key as NSString)
              if cachedInstance != nil {
                  print("Using old value!")
                  return cachedInstance as? T
              } else {
                  print("Using new value!")
                  let newInstance = factories[key]?()
                  cachedDependencies.setObject(newInstance, forKey: key as NSString)
                  return newInstance as? T
              }
          }
      }