After HTTP POST request UIView change delays

Question

I have use this code to make HTTP POST request:

let myURL = NSURL(string: serverURL)

let request = NSMutableURLRequest(URL: myURL!)

request.HTTPMethod = "POST"

request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)

let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
        data, response, error in

    if error != nil {
        print(error)
    } else {
        let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
        print(responseString)
        self.view.backgroundColor = UIColor.redColor()
    }

}

task.resume()

I have experience that the view's backgroundColor changes after several seconds from the print of the responseString.

Why is that and how can I make it simultaniously?

Thanks.

Answer 1

Always perform UI changes on main thread, so change your view's backgrondColor on the main thread like this way.

dispatch_async(dispatch_get_main_queue(),{
    self.view.backgroundColor = UIColor.redColor()
}

Answer 2

You need to perform UI changes on the main thread in order to make it faster, Because i think http requests are made asynchronously for example downloading an image. So in your code you can do as follows

dispatch_async(dispatch_get_main_queue(),{
    self.view.backgroundColor = UIColor.redColor()
}