title: What does -[NSURL length]: unrecognized selector sent to instance 0x1001c0360 mean
body: <p>I've been trying to get some example code interfaced with a Cocoa interface(It had been written using Carbon); however, when I attempted to replace</p>
  
  <pre><code> err = ExtAudioFileCreateNew(&amp;inParentDirectory, inFileName, kAudioFileM4AType, inASBD, NULL, &amp;fOutputAudioFile);
  </code></pre>
  
  <p>with</p>
  
  <pre><code>err = ExtAudioFileCreateWithURL(CFURLCreateWithString(NULL,(CFStringRef)inFileName,NULL),kAudioFileM4AType,inASBD, NULL,kAudioFileFlags_EraseFile, &amp;fOutputAudioFile);
  </code></pre>
  
  <p>I started to get these exceptions</p>
  
  <blockquote>
    <p>2011-09-25 10:27:31.701 tester[1120:a0f] -[NSURL length]: unrecognized
    selector sent to instance 0x1001c0360
        2011-09-25 10:27:31.701 tester[1120:a0f] -[NSURL length]: unrecognized selector sent to instance 0x1001c0360.</p>
  </blockquote>
  
  <p>I've looked at several other questions and answers and in all of those cases the problem was related to a <code>NSURL</code> being passed when a <code>NSString</code> was expected; however, I can't find where/if I'm doing that. I've looked at the documentation and as far as I can tell with my extremely limited knowledge of Apple's APIs. I'm not doing anything wrong.</p>
  
  <p>Any help would be greatly appreciated.</p>