title: iOS: Change contentsize of a UIScrollview using auto layout
body: <p>I'm implementing a form inside a <code>UIScrollView</code>. I'm trying to add some space at the bottom of the content of a scroll view when the keyboard is opened so the user can see all the fields. I put the form view inside the <code>UISCrollView</code> adding all the needed constraints with the following code:</p>
  
  <pre><code> [_infoView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[_infoView(1730)]" options:0 metrics:nil views:views]];
  
  [_scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_infoView]|" options:0 metrics:nil views:views]];
  
  [_scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_infoView]|" options:0 metrics:nil views:views]];
  
  [_scrollView addConstraint:[NSLayoutConstraint constraintWithItem:_infoView
                                                          attribute:NSLayoutAttributeCenterX
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:_scrollView
                                                          attribute:NSLayoutAttributeCenterX
                                                         multiplier:1
                                                           constant:0]];
  </code></pre>
  
  <p>As you can see, I specify in the first line the height of the form and the <code>scrollview</code> adapts its content size automatically. Now I want to increase the height of the form, so I've tried to reset the constraint for the height with a greater one but it won't work. Then I've tried to use the <code>[_scrollView setContentSize:]</code> method but this also won't work. Can anyone help me please?</p>