UIProgressView progress update very slow within AlamoFire (async) call

Inside an AlamoFire get request I’m trying to update my progress bar. Like so:

alamofireManager.request(.GET, urlPath, parameters: params).responseJSON{(request,response,JSON,error) in
    ...<code here>...
    dispatch_async(dispatch_get_main_queue(), {
        NSNotificationCenter.defaultCenter().postNotificationName(LoginVCHideSpinnerAndShowProgressBarName as String, object: self)
    ...<more code here>...

For some reasons this takes a few seconds to execute and if I use dispatch_sync instead the app just seems to get stuck at that point but the UI doesn’t freeze up (the activity indicator spinner keeps going).
I also want to point out that once the app hits this code it continues on to the code after it as if its been executed. It then is executed about 6 seconds later as if it wasn’t being called on the main thread.

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  • I have also just simply tried doing this instead of using a Notification.

    dispatch_async(dispatch_get_main_queue(), {
        loginVC.progressBar.hidden = false
        loginVC.indicator.hidden = true
        loginVC.progressBar.setProgress(0.1, animated: true)

    This seems to be slower than the Notification.

    I am very puzzled to why this is happening since I am telling it to update in the main thread. I am also confused why the notification is actually a little bit faster.

    Solutions Collect From Internet About “UIProgressView progress update very slow within AlamoFire (async) call”

    There’s a MUCH better way to do this in Alamofire. You can use the progress closure to automatically get a callback when a data transfer occurs on your data task. Here’s an example from the README monitoring progress for a download request. The same applies for a data request.

    let progressView = UIProgressView(progressViewStyle: .Bar)
    let params = ["foo": "bar"]
    let URLString = "http://httpbin.org/get"
    let request = Alamofire.request(.GET, URLString, parameters: params)
    request.progress { _, _, _ in
        progressView.setProgress(request.progress.fractionCompleted, animated: true)
    request.responseJSON { request, response, json, error in