DIKit

A tiny dependency injection container for Swift. No third-party dependencies, works on iOS and macOS.

Licensed under MIT.

Installation

.package(url: "https://github.com/PedroAugusto01/DIKit", from: "1.0.0")

.product(name: "DIKit", package: "DIKit"),

How it works

DIContainer maps a type to a factory closure. register stores the factory; resolve calls it (or returns the cached instance, for singletons):

let container = DIContainer()

container.register(Logging.self, scope: .singleton) { _ in ConsoleLogger() }
container.register(UserService.self) { resolver in
    UserService(logger: resolver.resolve(Logging.self))
}

let service: UserService = container.resolve(UserService.self)

• scope: .transient (the default) builds a fresh instance on every resolve.
• scope: .singleton builds the instance once, on first resolve, and reuses it after that.
• register(_:instance:) registers an already-built value as a singleton directly.
• Factories receive the container itself, so a service can resolve its own dependencies from it — nested resolution doesn't deadlock, since the container never holds its lock while running a factory.
• resolve(_:) traps with a descriptive message if nothing was registered for that type — a missing registration is a wiring mistake, not something to recover from at runtime. Use tryResolve(_:) if you'd rather get nil.

@Injected

For call sites that would rather not thread a container through every initializer:

final class ProfileViewModel {
    @Injected private var userService: UserService
}

By default it resolves from DIContainer.shared, the process-wide default container. Pass a different one (@Injected(container: myContainer)) when you're managing your own — most tests should.

Demo

swift run DIKitDemo

Tests

swift test