Simplest DI container in Swift

DIContainer.swift

public class DIContainer {
    public typealias Resolver = ([Any]) -> Any?
    static var resolvers: [ObjectIdentifier: Resolver] = [:]
    public static func register<T>(_ type: T.Type, resolver: @escaping Resolver) {
        resolvers[ObjectIdentifier(type)] = resolver
    }
    
    public static func resolve<T>(_ type: T.Type, args: Any...) -> T? {
        guard let resolver = resolvers[ObjectIdentifier(type)] else { return nil }
        return resolver(args) as? T
    }
}

Usage

protocol Valuable {
    var value: String { get }
}

struct Value: Valuable {
    var value: String
}

DIContainer.register(Valuable.self) { args in
    guard let text = args.first as? String else { return nil }
    return Value(value: text)
}

let value = DIContainer.resolve(Valuable.self, args: "test") // Optional(Value(value: “test”))