title: How to reset to identity the "current transformation matrix" with some CGContext function?
body: <p>I'm doing a series of translations and rotations on the CTM and at some point I need to reset it to identity before going further with transformations.</p>
  
  <p>I can't find any proper way to do it (obviously, there should have been a function named CGContextSetCTM or so) and since efficiency is the key, I don't want to use CGContextSaveGState/CGContextRestoreGState...</p>