title: duplicate symbols for architecture arm64(xcode 8)
body: <p>It show this after I use <code>cocopod</code> to install the tools
  and it does not work even I deleted the <code>libPods-MagicSquare-SDWebImage.a</code></p>
  
  <p><img src="https://i.stack.imgur.com/LtyUB.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/33K6L.png" alt="enter image description here"></p>