title: UIWebView shows blank for some iOS 9 users (rare and strange)
body: <p>I have a UIWebView on a viewController, normally it loads a web page of my own website. But recently I found that UIWebView appears to be blank for a few users. Just a gray blank screen(I set it's backgroundColor to gray). </p>
  
  <p>I'm using:</p>
  
  <pre><code>UIWebView* webView = [[UIWebView alloc] initWithFrame:self.view.bounds];
  webView.scalesPageToFit = YES;
  webView.delegate = self;
  webView.scrollView.delegate = self;
  webView.opaque = NO;
  webView.backgroundColor = [UIColor lightGrayColor];
  [self.view addSubview:webView];
  self.webView = webView;
  </code></pre>
  
  <p>and:</p>
  
  <pre><code>NSURL *url = [NSURL URLWithString:urlString];
  NSURLRequest *request = [NSURLRequest requestWithURL:url];
  [self.webView loadRequest:request];
  </code></pre>
  
  <p>I have come to known the following facts: </p>
  
  <ol>
  <li><p>It's not a https url, and I have Allow Arbitrary Loads in Info.plist.</p></li>
  <li><p><strong>Those users were able to see contents of that web page on that UIWebView before.</strong> Then suddenly one day, without upgrading, reinstalling the app or the system, the UIWebView turns blank for them. I'm pretty sure it's the same url link.</p></li>
  <li><p>Those users are able to access that specific link in their safari. And they are able to access urls with different hosts in my app.</p></li>
  <li><p>If they manually kill the app and reopen it, it's still blank. <strong>Even when they delete the app and reinstall it from the AppStore, it's still blank.</strong></p></li>
  <li><p>Then after several days, without anything done particularly, the UIWebView returns to normal. The problem disappeared.</p></li>
  <li><p>Once I was able to borrow a phone with that problem from a user. When I plug the phone in and ran debug from XCode, it immediately returns to normal.</p></li>
  </ol>
  
  <p>This bug is driving me crazy for it's strange behavior, and it's really had to reproduce. Up to now I've got 4 reports of this bug, all of them are from iOS 9 users, no particular device. That problematic web page is powered by angularJS, if that helps.</p>
  
  <p>I don't have any clue by now. Any suggestion would help. Thanks in advance!</p>