NJKWebViewProgressView as Progress Bar on UIView

[loretoparisi]

Hi,
I'm trying to use the NJKWebViewProgressView as progress on a UIView like:

- (void)viewDidLoad {
CGFloat progressBarHeight = 2.f;
    CGRect navigaitonBarBounds = self.view.bounds;
    CGRect barFrame = CGRectMake(0, progressBarHeight + 5.0 , navigaitonBarBounds.size.width, progressBarHeight);
    _progressView = [[NJKWebViewProgressView alloc] initWithFrame:barFrame];
    _progressView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleTopMargin;
    [_progressView setProgress:0.2 animated:NO];
    [self.container addSubview:_progressView];
    //...

so without having any UIWebView delegate and trying to update the progress manually. If I try to change the progress it seems nothing happens a part in the viewDidLoad method:

-(IBAction)discover:(id)sender {

    float progress=0.5;
    dispatch_async(dispatch_get_main_queue(), ^{
        [_progressView setProgress:progress animated:YES];
    });

where self.container is a UIView.
Where I'm wrong or missing something in the code?