SMSync

//
//  SMSync.swift
//  TableExample
//
//  Created by sid on 11/08/14.
//  Copyright (c) 2014 Sergio Martinez-Losa. All rights reserved.
//

import Foundation

/**
    A semaphotre class that waits till async executions ends

    example:

    var request : HTTPRequest = HTTPRequest()

    var callback2 : (() -> ()) = { () -> () in

        // something for callback

        SMSync.endSync()
    }

    SMSync.beginSync({() -> () in

        request.method(callback);
    })

*/

typealias Completion = (() -> ())

var semaphone : dispatch_semaphore_t!

class SMSync : NSObject
{
    class func beginSync(completion : Completion)
    {
        semaphone = dispatch_semaphore_create(0)
    
        completion();
    
        while (dispatch_semaphore_wait(semaphone, DISPATCH_TIME_NOW) != 0)
        {
            NSRunLoop.currentRunLoop().runUntilDate(NSDate(timeIntervalSinceNow:0))
        }
    }
    
    class func endSync()
    {
        SMSync.performSync(semaphone)
    }
    
    class func performInMainThreads(completion : Completion)
    {
        dispatch_async(dispatch_get_main_queue()) {
    
            completion();
        }
    }
    
    private class func performSync(sem : dispatch_semaphore_t)
    {
        dispatch_semaphore_signal(sem);
    }
}