title: ios：My app,first login is alright, logout my app and login is ok, but if I double-click home to kill my app and login, it will crash
body: <p>Recently, I get an old project, after modified some codes, such as <code>Enable Bitcode</code> to <code>NO</code>, and <code>ATS</code> to adapte iOS9.But there comes an issue:
  in my app,For first time login is alright, logout my app and again login is ok, but if I double-click home to kill my app and try login, it will crash.</p>
  <p>Someone meet with this issue?</p>
  <h1>EDIT:I have get the reason, if in iOS8 it works well,but if in the iOS9, it will crash, I also don't get the solution,is the code is too old?</h1>