title: Efficient NSArray and float * conversion
body: <p>I know it's possible to convert between <code>float *</code> and NSArray (or NSMutableArray) with</p>
  
  <pre><code>for (int i=0; i&lt;[array count]; i++) x[i] = [[array objectAtIndex:i] floatValue];
  
  for (int i=0; i&lt;N; i++) [array addObject:[NSNumber numberWithFloat:x[i]]];
  </code></pre>
  
  <p>But those both use for-loops which are slow and inefficient. I'd like to see <code>x = [array toFloatArray]</code>. Almost anything that uses images/anything iOS related and requires lower level libraries (BLAS, LAPACK, etc) requires this conversion, and it would be nice to speed it up.</p>