title: Does [NSData getBytes: length:] change position in buffer?
body: <p>I have some NSData instance with 2 bytes of different value.</p>
  
  <p>Will calling getBytes: of any kind (length, range...) also advance the current position in the buffer?</p>
  
  <p>Example:</p>
  
  <pre><code>NSData *data = ...; // 2 bytes data
  [data getBytes:&amp;whatever1 length:1]; // reading first byte
  [data getBytes:&amp;whatever2 length:1]; // reading first OR second byte?
  </code></pre>
  
  <p>Will the contents that I get on each time getBytes:length: is called be the same first byte in the NSData instance or will the first call advance the next call to read from the second byte?</p>
  
  <p>Thanks!</p>