title: What constitutes a private API in an iPhone app?
body: <p>I'm fairly new to Objective-C and am confused on what falls under the unbrella of a "private API" that could cause Apple to reject my app. Does this include adding methods to existing classes? For example, I found some code on stackoverflow to recolor the tab bar icons for UITabBars with this extension to the UITabBarItem class. Is this considered a "private API"? If not, what does?</p>
  
  <pre><code>@interface UITabBar (ColorExtensions)
  - (void)recolorItemsWithImage:(UIImage *)image shadowColor:(UIColor *)shadowColor shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur;
  @end
  </code></pre>