title: NSNumber from CGFloat
body: <p>Is there a safe way to "convert" a <code>CGFloat</code> to a <code>NSNumber</code> ?</p>
  
  <p><code>NSNumber</code> has the <code>numberWithFloat:</code> and <code>numberWithDouble:</code> methods but <code>CGFloat</code> being defined as <code>float</code> or <code>double</code> depending on the platform, it seems risky to use either one of them.</p>
  
  <p>Or is <code>numberWithDouble:</code> safe to use with a <code>CGFloat</code>, as it is the one with the more precision ?</p>