title: AttributedString in UINavigationBar not showing both lines of text
body: <p>I am trying to set a two line label in my UINavigationBar. When I do the following, it only shows one line (the part before the line break).</p>
  
  <pre><code>NSString *title = @"First line of title is bigger\nSecond line of title is smaller";
  NSDictionary *attribute1 = @{NSForegroundColorAttributeName: [UIColor colorWithRed:148/255.0f green:147/255.0f blue:147/255.0f alpha:1],
                               NSFontAttributeName: [UIFont boldSystemFontOfSize: 14.0f]};
  NSDictionary *attribute2 = @{NSForegroundColorAttributeName: [UIColor colorWithRed:148/255.0f green:147/255.0f blue:147/255.0f alpha:1],
                               NSFontAttributeName: [UIFont boldSystemFontOfSize: 10.0f]};
  const NSRange line1Range = {0, 29};
  const NSRange line2Range = {31, 30};
  
  NSMutableAttributedString *attributedText =[[NSMutableAttributedString alloc] initWithString:title];
  [attributedText setAttributes: attribute1 range:line1Range];
  [attributedText setAttributes: attribute2 range:line2Range];
  
  UILabel *label = [[UILabel alloc] init];
  label.attributedText=attributedText;
  self.navigationItem.titleView = label;
  [self.navigationItem.titleView sizeToFit];
  </code></pre>
  
  <p>For comparison, the following shows both line. The following is for comparison only. The top version is what I need.</p>
  
  <pre><code>UILabel *label = [[UILabel alloc] init];
  label.backgroundColor = [UIColor clearColor];
  label.numberOfLines = 2;
  label.font = [UIFont boldSystemFontOfSize: 14.0f];
  label.textColor = [UIColor colorWithRed:148/255.0f green:147/255.0f blue:147/255.0f alpha:1];
  label.text = @"First line of title is bigger\nSecond line of title is smaller";
  
  self.navigationItem.titleView = label;
  [self.navigationItem.titleView sizeToFit];
  </code></pre>
  
  <p>Any help getting the top version to work correctly?</p>