title: How to set text color for all subviews?
body: <p>For example, I create a <code>UIView</code> which has some <code>UILabel</code> and <code>UIButton</code> subviews inside. All of the subviews has different text colors. </p>
  
  <p>Is there an easy way to set text color for all subviews and cancel it? It should works like mask?</p>