title: How to manage a BOOL variable?
body: <p>I'm using a variable "volume" </p>
  
  <pre><code>@property BOOL * volume;
  </code></pre>
  
  <p>to set Volume On (YES) or Off (NO)</p>
  
  <pre><code>- (IBAction)manageVolume:(UIButton *)sender {
      if (_volume == TRUE) {
          _volume = !_volume; 
  //      code...
      } else {
          _volume = !_volume;
  //      code...
          }
      }
  </code></pre>
  
  <p>It Works but it return three alerts:</p>
  
  <ul>
  <li><p><code>if (_volume == TRUE) {</code> returns <code>Comparison between pointer and integer ('BOOL *' (aka 'signed char *') and 'int')</code></p></li>
  <li><p><code>_volume = !_volume;</code> returns <code>Incompatible integer to pointer conversion assigning to 'BOOL *' (aka 'signed char *') from 'int'</code> </p></li>
  </ul>
  
  <p>How  can I solve? Thank you!</p>