https://qooah.com/2014/06/13/%e4%be%86%e7%9c%8b%e7%9c%8b%e5%9c%a8wwdc%e4%b8%8aapple%e5%b1%95%e7%a4%ba%e7%94%b1metal%e5%bc%95%e6%93%8e%e8%a3%bd%e4%bd%9c%e7%9a%84%e9%81%8a%e6%88%b2%ef%bc%81/