XCTestCase extension for simplifying waiting for expectations

XCTestCase+OffTopic.swift

//
//  XCTestCase+OffTopic.swift
//
//  Created by Steve Wilford on 21/11/2015.
//  Copyright © 2015 Off Topic. All rights reserved.
//

import XCTest

extension XCTestCase {

    func wait(delay: NSTimeInterval, forExpectationWithDescription description: String, timeout: NSTimeInterval, handler: () -> ()) {
        wait(delay, forExpectationWithDescription: description, timeout: timeout, handler: handler, timeoutHandler: nil)
    }
    
    func wait(delay: NSTimeInterval, forExpectationWithDescription description: String, timeout: NSTimeInterval, handler: () -> (), timeoutHandler: XCWaitCompletionHandler? = nil) {
        
        let expectation = self.expectationWithDescription(description)
        
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(delay * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) {
            handler()
            expectation.fulfill()
        }
        
        self.waitForExpectationsWithTimeout(timeout, handler: timeoutHandler)   
    }
}