title: How to determine the content size of a WKWebView?
body: <p>I am experimenting with replacing a dynamically allocated instance of UIWebView with a WKWebView instance when running under iOS 8 and newer, and I cannot find a way to determine the content size of a WKWebView.</p>
  
  <p>My web view is embedded within a larger UIScrollView container, and therefore I need to determine the ideal size for the web view.  This will allow me to modify its frame to show all of its HTML content without the need to scroll within the web view, and I will be able to set the correct height for the scroll view container (by setting scrollview.contentSize).</p>
  
  <p>I have tried sizeToFit and sizeThatFits without success.  Here is my code that creates a WKWebView instance and adds it to the container scrollview:</p>
  
  <pre><code>// self.view is a UIScrollView sized to something like 320.0 x 400.0.
  CGRect wvFrame = CGRectMake(0, 0, self.view.frame.size.width, 100.0);
  self.mWebView = [[[WKWebView alloc] initWithFrame:wvFrame] autorelease];
  self.mWebView.navigationDelegate = self;
  self.mWebView.scrollView.bounces = NO;
  self.mWebView.scrollView.scrollEnabled = NO;
  
  NSString *s = ... // Load s from a Core Data field.
  [self.mWebView loadHTMLString:s baseURL:nil];
  
  [self.view addSubview:self.mWebView];
  </code></pre>
  
  <p>Here is an experimental didFinishNavigation method:</p>
  
  <pre><code>- (void)webView:(WKWebView *)aWebView
                               didFinishNavigation:(WKNavigation *)aNavigation
  {
      CGRect wvFrame = aWebView.frame;
      NSLog(@"original wvFrame: %@\n", NSStringFromCGRect(wvFrame));
      [aWebView sizeToFit];
      NSLog(@"wvFrame after sizeToFit: %@\n", NSStringFromCGRect(wvFrame));
      wvFrame.size.height = 1.0;
      aWebView.frame = wvFrame;
      CGSize sz = [aWebView sizeThatFits:CGSizeZero];
      NSLog(@"sizeThatFits A: %@\n", NSStringFromCGSize(sz));
      sz = CGSizeMake(wvFrame.size.width, 0.0);
      sz = [aWebView sizeThatFits:sz];
      NSLog(@"sizeThatFits B: %@\n", NSStringFromCGSize(sz));
  }
  </code></pre>
  
  <p>And here is the output that is generated:</p>
  
  <pre><code>2014-12-16 17:29:38.055 App[...] original wvFrame: {{0, 0}, {320, 100}}
  2014-12-16 17:29:38.055 App[...] wvFrame after sizeToFit: {{0, 0}, {320, 100}}
  2014-12-16 17:29:38.056 App[...] wvFrame after sizeThatFits A: {320, 1}
  2014-12-16 17:29:38.056 App[...] wvFrame after sizeThatFits B: {320, 1}
  </code></pre>
  
  <p>The sizeToFit call has no effect and sizeThatFits always returns a height of 1.</p>