title: Ignoring return value of function declared with "warn_unused_result" attribute
body: <p>We start having this warning on all the <code>becomeFirstResponder</code> function call in our Objective-C code. </p>
  
  <blockquote>
    <p>Ignoring return value of function declared with "warn_unused_result" attribute</p>
  </blockquote>
  
  <pre><code>[self.phoneNumberField becomeFirstResponder]; // warning here!!!
  </code></pre>
  
  <p>What's the best way to suppress this warning here? </p>
  
  <hr>
  
  <p>Edit: I also tried this,</p>
  
  <pre><code>BOOL ignore = [self.emailField becomeFirstResponder]; 
  </code></pre>
  
  <p>But with that, Xcode has warning about the variable <code>ignore</code> is not used :(</p>
  
  <hr>
  
  <p>I also tried this,</p>
  
  <pre><code>BOOL ignore = [self.phoneNumberField becomeFirstResponder];
  if (ignore) {
  
  }
  </code></pre>
  
  <p>The warnings is gone in this case. But I don't think I can even past my own code review. It is too ugly!</p>