问iOS应用程序:使用swift进行登录后交换Swapping控制器有明显的延迟

EN

    func switchRootViewController(rootViewController: UIViewController, animated: Bool, completion: (() -> Void)?) {
    if animated {
        UIView.transitionWithView(self.window!, duration: 0.5, options: .TransitionCrossDissolve, animations: {
            let oldState: Bool = UIView.areAnimationsEnabled()
            UIView.setAnimationsEnabled(false)
            self.window!.rootViewController = rootViewController
            UIView.setAnimationsEnabled(oldState)
            }, completion: { (finished: Bool) -> () in
                if (completion != nil) {
                    completion!()
                }
        })
    } else {
        self.window!.rootViewController = rootViewController
    }
}

   api.postMulti(apiKey, contentType: "application/json", payLoad: payLoad, urlString: urlString, parameter: parameter){ (succeeded: Int, msg: String) -> () in

        var alert = UIAlertView(title: "Failed", message: msg, delegate: nil, cancelButtonTitle: "Okay")

        if succeeded == 422 {
            alert.title = "Failed"
            alert.message = "Username is already in use. Please selecet another one!"
        }

        else if succeeded == 500{
            alert.title = "Failed"
            alert.message = "Internal Server Error. Unable to process Request!"
        }

        else if succeeded == 200{
            //save to internal DataBase table: User
            let entityDescription = NSEntityDescription.entityForName("User", inManagedObjectContext: self.managedObjectContext!)

            let users = User(entity: entityDescription!, insertIntoManagedObjectContext: self.managedObjectContext)

            users.username = self.userName.text

            var error: NSError?

            self.managedObjectContext?.save(&error)

            if let err = error {
                println(err.localizedFailureReason)
            } else {

                self.userName.text = ""
                alert.title = "Success"
                alert.message = "Loading App..."



                let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
                var secondViewController: EveryTimeRun = mainStoryboard.instantiateViewControllerWithIdentifier("everytime") as! EveryTimeRun

                self.switchRootViewController(secondViewController, animated: true, completion: nil)




                self.window?.makeKeyAndVisible()


            }
        }

        // Move to the UI thread
        dispatch_async(dispatch_get_main_queue(), { () -> Void in
            // Show the alert
            alert.show()
        })
    }

        func postMulti(apikey: String, contentType: String, payLoad: Dictionary<String,Dictionary<String,String>>, urlString: String, parameter: String, postCompleted : (succeeded: Int, msg: String) -> ()){

    let joinedUrl = urlString + parameter
    let url = NSURL(string: joinedUrl)
    let request = NSMutableURLRequest(URL: url!)

    var session = NSURLSession.sharedSession()
    request.HTTPMethod = "POST"
    request.addValue(contentType, forHTTPHeaderField: "Content-Type")
    request.addValue(apikey, forHTTPHeaderField: "apikey")
    var error: NSError?


    let payLoadJSON = NSJSONSerialization.dataWithJSONObject(payLoad, options: nil, error: &error)
    request.HTTPBody = payLoadJSON

    var task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
        var strData = NSString(data: data, encoding: NSUTF8StringEncoding)


        var err: NSError?
        var json = NSJSONSerialization.JSONObjectWithData(data, options: .MutableLeaves, error: &err) as? NSDictionary
        // Did the JSONObjectWithData constructor return an error? If so, log the error to the console
        if(err != nil) {
            //            println(err!.localizedDescription)
            let jsonStr = NSString(data: data, encoding: NSUTF8StringEncoding)

            postCompleted(succeeded: 0, msg: "Portal is not reachable. Please try again later")
        }
        else {
            // The JSONObjectWithData constructor didn't return an error. But, we should still
            // check and make sure that json has a value using optional binding.
            if let parseJSON = json {
                // Okay, the parsedJSON is here, let's get the value for 'success' out of it
                if let statusCode = parseJSON["statusCode"] as? Int {

                    postCompleted(succeeded: statusCode, msg: "")
                }
            }
            else {
                // Woa, okay the json object was nil, something went worng. Maybe the server isn't running?
                let jsonStr = NSString(data: data, encoding: NSUTF8StringEncoding)

                postCompleted(succeeded: 1, msg: "Portal is not reachable. Please try again later")
            }
        }
    })

    task.resume()
}