There is no sense in progress property until it is set by setProgress be...

.gitignore

@@ -0,0 +1,2 @@
+DemoApp.xcodeproj/project.xcworkspace/xcuserdata
+DemoApp.xcodeproj/xcuserdata

DemoApp/ViewController.m

@@ -68,6 +68,7 @@ -(void)loadGoogle
 -(void)webViewProgress:(NJKWebViewProgress *)webViewProgress updateProgress:(float)progress
 {
     [_progressView setProgress:progress animated:YES];
+    NSAssert(progress == _progressView.progress, @"Progress is not set correctly");
     self.title = [_webView stringByEvaluatingJavaScriptFromString:@"document.title"];
 }
 

NJKWebViewProgress.podspec

@@ -5,7 +5,7 @@ Pod::Spec.new do |s|
   s.summary      = "UIWebView progress interface."
   s.homepage     = "https://github.com/ninjinkun/NJKWebViewProgress"
   s.authors      = { "ninjinkun" => "ninjin@mac.com" }
-  s.source       = { :git => "https://github.com/ninjinkun/NJKWebViewProgress.git", :tag => "v#{s.version}" }
+  s.source       = { :git => "https://github.com/AlexeyAfanasyev/NJKWebViewProgress.git" }
   s.platform     = :ios, '4.3'
   s.requires_arc = true
   s.subspec 'Core' do |ss|

NJKWebViewProgress/NJKWebViewProgressView.m

@@ -49,6 +49,7 @@ -(void)setProgress:(float)progress
 
 - (void)setProgress:(float)progress animated:(BOOL)animated
 {
+    _progress = progress;
     BOOL isGrowing = progress > 0.0;
     [UIView animateWithDuration:(isGrowing && animated) ? _barAnimationDuration : 0.0 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
         CGRect frame = _progressBarView.frame;