title: Strange behavior of UIScrollView with Constraints and RTL
body: <p>I have an horizontal scroll view on which i add views dynamically.
  On LTR languages everything work fine, i add views one after the other from left to right.
  On RTL the problem is that the views always added to the left of the scroll instead of to the right like in every other controller, the <strong>really</strong> strange staff that the order of the views is added correctly, to the left of the first view so they are ordered from right to left but outside of the scroll view on -x.</p>
  
  <p>Here is my code when i add a new View:</p>
  
  <pre><code>Tag* tag = [self.storyboard instantiateViewControllerWithIdentifier:@"tag" ];
  [_scroller addSubview:tag.view];
  [tags addObject:tag];
  Tag* prev = nil
  for (Tag* tag in tags)
  {
      if (prev == nil)
      {
          [_scroller addConstraint:[NSLayoutConstraint constraintWithItem:tag.view 
                                                         attribute:NSLayoutAttributeLeading                                                                                          
                                                         relatedBy:NSLayoutRelationEqual
                                                                       toItem:_scroller
                                                                    attribute:NSLayoutAttributeLeading
                                                                   multiplier:1.0f
                                                                     constant:0]];
      }
      else
      {
          [_scroller addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"[prev]-10-[tag]"
                                                                            options:0
                                                                            metrics:nil
                                                                              views:@{@"tag" : tag.view, @"prev" : prev.view}]];
      }
  
      [_scroller addConstraint:[NSLayoutConstraint constraintWithItem:tag.view
                                                            attribute:NSLayoutAttributeCenterY
                                                            relatedBy:NSLayoutRelationEqual
                                                               toItem:_scroller
                                                            attribute:NSLayoutAttributeCenterY
                                                               multiplier:1.0f
                                                                 constant:0]];
      prev = tag;
  
  }
  </code></pre>
  
  <p>Here is an image of how it suppose to work on LTR and RTL and how it actually works
  <img src="https://i.stack.imgur.com/OyczB.png" alt="enter image description here"></p>