container.swift

class Container {
    typealias Resolver = () -> AnyObject
    private var _resolvers: [String: Resolver] = [:]

    func register<T: AnyObject>(resolver: @autoclosure () -> T) {
        let name = NSStringFromClass(T.self)
        _resolvers[name] = resolver
    }

    func get<T: AnyObject>() -> T {
        let name = NSStringFromClass(T.self)
        if let resolver = _resolvers[name] {
            return resolver() as T
        } else {
            fatalError("no registration for requested type")
        }
    }
}

prefix operator <- {}
infix operator <- {}

prefix func <-<T: AnyObject>(container: Container) -> T {
    return container.get()
}

func <-<T: AnyObject>(container: Container, registration: @autoclosure () -> T) {
    container.register(registration)
}

example.swift

class A: NSObject { }
class B: NSObject { }

let a = A()
let b = B()

let container = Container()
container <- a // singleton
container <- B() // factory

class Dependent {
    let a: A = <-container
    let b: B = <-container
}

let dep = Dependent()
if dep.a == a { print("a ok") }
if dep.b != b { print("b ok") }