title: Warning : Format string is not a string literal (potentially insecure)
body: <p>I get the warning in the NSLog line</p>
  
  <pre><code>Format string is not a string literal(potentially insecure)
  </code></pre>
  
  <p>From the following code</p>
  
  <pre><code>NSMutableString  *MarqueeMessage = [[NSMutableString alloc]init];
  [MarqueeMessage appendString:@"Abc"];
  NSString *immutableString = MarqueeMessage;
  NSLog(immutableString);
  </code></pre>
  
  <p>May I ask why after I changed the line into the following code, the warning is gone?</p>
  
  <pre><code>NSLog(immutableString,nil);
  </code></pre>