StreamSample.swift

class Stream<T> {
    var subscribers: [(T) -> Void] = []
    
    func subscribe(subscriber: (T) -> Void) {
        subscribers.append(subscriber)
    }
    
    func publish(message: T) {
        for subscriber in subscribers {
            subscriber(message)
        }
    }
}

let stringStream = Stream<String>()
stringStream.subscribe { message in
    println("message received: \(message)")
}
stringStream.publish("test")
stringStream.publish("demo")

let intStream = Stream<Int>()
intStream.subscribe { integer in
    println("integer received: \(integer)")
}
intStream.subscribe { integer in
    println("number received: \(integer)")
}
intStream.publish(1)
intStream.publish(100)