Synchronous vs. Asynchronous WatchKit call

gistfile1.swift

    func application(application: UIApplication!, handleWatchKitExtensionRequest userInfo: [NSObject : AnyObject]!, reply: (([NSObject : AnyObject]!) -> Void)!) {
        /* Synchronous
        let response : (DateTime?, NSError?) = Network.fetchDateTime()
        if let checkedDateTime = response.0 {
            reply(["response": NSKeyedArchiver.archivedDataWithRootObject(checkedDateTime)])
        }
        else if let checkedError = response.1 {
            reply(["error": NSKeyedArchiver.archivedDataWithRootObject(checkedError)])
        }
        else {
            reply(["error": NSKeyedArchiver.archivedDataWithRootObject("whoops")])
            NSLog("Error")
        }
*/
        /*Asynchronous*/
        let sem = dispatch_semaphore_create(0)
        Network.asynchFetchDateTime {
            (dateTime, error) -> Void in
            if let checkedDateTime = dateTime {
                reply(["response": NSKeyedArchiver.archivedDataWithRootObject(checkedDateTime)])
            }
            else if let checkedError = error {
                reply(["error": NSKeyedArchiver.archivedDataWithRootObject(checkedError)])
            }
            dispatch_semaphore_signal(sem)
        }
        dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER)
    }