title: Set text vertical center in NSTextField
body: <p>In a certain height NSTextField , the layout would be like this if text's size is small</p>
  
  <p><img src="https://i.stack.imgur.com/HdUPO.jpg" alt="enter image description here"></p>
  
  <p>the text is flowing to the top ,how to make the text center like this:</p>
  
  <p><img src="https://i.stack.imgur.com/QL77o.jpg" alt="enter image description here"></p>