title: How to remove the top and bottom padding of UIButton, when create it using auto layout?
body: <p>When create UIButton with auto layout, the <code>intrinsicContentSize</code> always contain different top/bottom padding according to different text font size. I try to set <code>contentEdgeInsets</code>, but it not really works for top/bottom padding. </p>
  
  <p>How to fix the padding to 0 or any constant value?</p>