title: libc++abi.dylib: terminate_handler unexpectedly threw an exception
body: <blockquote>
    <p>Objective: {objective 0x7fb7a49de030: &lt;750:216, 250:2804> +
    &lt;750:-9.93411e-08>*0x7fb7a4d254b0.negError{id: 1392} +
    &lt;750:-9.93411e-08>*UIButton:0x7fb7a4b87750.Width{id: 1233}}
    libc++abi.dylib: terminate_handler unexpectedly threw an exception</p>
  </blockquote>
  
  <p>when i push or present a ViewController it crashed,this is the crash message,how to resolve it ?</p>