title: Unable to compile this on Xcode due to AudioFileID
body: <p><a href="https://i.stack.imgur.com/OCZ3o.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OCZ3o.jpg" alt="enter image description here" /></a>I'm trying to code using examples in &quot;Learning Core Audio&quot; book. This is the first example
  There's a piece of code where I need to declare</p>
  <pre><code>AudioFileID audiofile
  </code></pre>
  <p>This example has no other imports.
  Any clues or any new files to include. I'm running Xcode version 12.4
  This project is a command line project on mac OS and am using Objective C</p>
  <p>Error is here</p>
  <pre><code>//
  //  main.m
  //  CAMetadata
  //
  //
  
  #import &lt;Foundation/Foundation.h&gt;
  
  
  int main(int argc, const char * argv[]) {
    @autoreleasepool {
      if (argc &lt; 2){
        // insert code here...
          printf(&quot;Usage: CAMetadata /full/path/to/audiofile\n&quot;);
      }
    }
  
    NSString * audioFilePath = [[NSString stringWithUTF8String:argv[1]] stringByExpandingTildeInPath];
    NSURL *audioFileURL = [NSURL fileURLWithPath:audioFilePath];
    **AudioFileID audioFile;**
    OSStatus theErr = noErr;
    theErr = AudioFileOpenURL((CFURLRef) audioFileURL, kAudioFileReadPermission , 0, &amp;audioFileURL);
  
  
  
  
    return 0;
  } // end of main
  </code></pre>