swift Go like channels

channel.swift

import Foundation
// Playground - noun: a place where people can play
class Channel<T> {
    
    var stream: Array<T>
    let queue: dispatch_queue_t
    let semaphore: dispatch_semaphore_t
    
    init() {
        self.stream = []
        self.semaphore = dispatch_semaphore_create(0)
        self.queue = dispatch_queue_create("channel.queue.", DISPATCH_QUEUE_CONCURRENT)
    }
    
    func write(value: T) {
        dispatch_async(self.queue) {
            self.stream += value
            dispatch_semaphore_signal(self.semaphore)
        }
    }
    
    func recv() -> T {
        var result:T?
        dispatch_sync(self.queue) {
            dispatch_semaphore_wait(self.semaphore, DISPATCH_TIME_FOREVER)
            result = self.stream.removeAtIndex(0)
        }
        return result!
    }
}

let chan: Channel<Int> = Channel()
let delay = 1.5 * Double(NSEC_PER_SEC)
let time = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))
dispatch_after(time, dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
    chan.write(20)
})

chan.write(1)
chan.write(5)
chan.write(2)


let x1 = chan.recv()
let x2 = chan.recv()
println((x1, x2))                      // 1, 2
let name = "result \(x1)"              // "result 1"
let name2 = "result \(x2)"             // "result 5"
let name3 = "result \(chan.recv())"    // "result 2"
let name4 = "result \(chan.recv())"    // "result 20" after 1.5 secs