title: Remove first bytes of a unsigned char*
body: <p>I'm currently working on a project where I need to work with unsigned char* and unwanted bytes in there. I'll describe the situation:</p>
  
  <p>1/ I have an iOS app that loads an image (UIImage).</p>
  
  <p>2/ I transform this UIImage into a unsigned char* (thanks to the ImageHelper given by PaulSoft <a href="http://paulsolt.com/2010/09/ios-converting-uiimage-to-rgba8-bitmaps-and-back/" rel="nofollow">here</a></p>
  
  <p>3/ I send this unsigned char* to a library that works his magic on the image.</p>
  
  <p>4/ The library sends me back an unsigned char* with complementary information at the beginning of the array.</p>
  
  <p>And here I am. I want to remove the 13 firsts bytes of this array, and I have no idea how to do so.
  I've tried converting it to a NSString*, cropping it and get it back. Same thing with NSData*.
  I am definitely not a pro in Objective-C, so I'm open to every ideas you can have. Please feel free to ask me anything if I wasn't clear enough.</p>
  
  <p>Best regards;</p>
  
  <p>Chris.</p>