Dependency injection using Property wrappers (like @EnvironmentObject in SwiftUI). Core code from: https://medium.com/@anuragajwani/dependency-injection-in-ios-and-swift-using-property-wrappers-f411117cfdcf

AppContainer.swift

/* SET */
Container.shared.register(type: User.self, User())
Container.shared.set(User(), forKey: "SecondUser")
                    
/* GET */
let sameUser = Container.shared.resolve(User.self)
let secondUser = Container.shared.get("SecondUser", of: User.self)
                    
/* REMOVE */
$user.deregister() // This will remove "User" from factory.
Container.shared.remove("SecondUser") // Remove second user.

// MARK: - Implementation

class Container {
    static let shared = Container()
    
    private var factoryDict: [String: () -> Any] = [:]
    
    func register<Service>(type: Service.Type, _ factory: @autoclosure @escaping () -> Service) {
        set(factory, forKey: String(describing: type.self))
    }
    
    func resolve<Service>(_ type: Service.Type) -> Service {
        get(String(describing: type.self), of: type.self)!
    }
    
    func deregister<Service>(_ type: Service.Type) {
        remove(String(describing: type.self))
    }
    
    func set(_ value: @autoclosure @escaping () -> Any, forKey key: String) {
        factoryDict[key] = value
    }
    
    func get<Service>(_ key: String, of type: Service.Type) -> Service? {
        factoryDict[key]?() as? Service
    }
    
    func remove(_ key: String) {
        factoryDict[key] = nil
    }
}

@propertyWrapper
struct Inject<Type> {
    var type: Type
    init() {
        self.type = Container.shared.resolve(Type.self)
    }
    var wrappedValue: Type {
        get { self.type }
        mutating set {
            self.type = newValue
        }
    }
    
    var projectedValue: Inject<Type> { return self }
    
    func deregister() {
        Container.shared.deregister(Type.self)
    }
}