title: terminating with uncaught exception of type NSException (objective C)
body: <p>The program closes at Objective-c. Please help solve my problem.
  Error: </p>
  
  <blockquote>
    <p>*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSNull length]: unrecognized
    selector sent to instance 0x115289cf0'</p>
  </blockquote>
  
  <p><a href="https://i.stack.imgur.com/pCcwg.png" rel="nofollow noreferrer">enter image description here</a></p>