title: Use of undeclared identifier in main.m
body: <p>I'm starting with Objective-C and I have a problem.</p>
  
  <p>The compiler is giving me this error message:</p>
  
  <pre><code>Semantic Issue: Use of undeclared identifier
  </code></pre>
  
  <p>And this is the <code>main.m</code> code:</p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  
  #import "HMJAppDelegate.h"
  
  int main(int argc, char *argv[]) {
      @autoreleasepool {
          return UIApplicationMain(argc, argv, nil, NSStringFromClass([HMJAppDelegate class]));
      } 
  }
  </code></pre>
  
  <p>This error is in the main.m file.</p>
  
  <p>How can I fix the problem?</p>