Question

In Xcode ui builder when one set the UIBarStyle of the UIToolBar (such as BlackTranslucent, for example), the UIToolBarItem matches the background images to it. How does the UIToolBarItem know which style it should use?

I’m trying to do a put a custom colored image on top of the regular background tile (programatically merge a given image on top of the background image). I want to the code to be generalizable enough so that it is able to handle all UIBarStyles. That means I want to know when UIToolBarItem decides which background to use and intercept it so I can compose the button image on the fly.

Answer 1

Without being able to see apple’s implementation of UIBarbuttonItem, I posit that they do not, in fact, know what the style of their UIToolbar is. If you look closely, they have the same alpha as their toolbar, and the same overlay (indicative of a subview). Therefore, any image that is below this highlighted layer, added as a subview, should conform to the UIToolbar’s style. If you want to use multiple images though (one for each barStyle), you can determine it with self.myToolbar.barStyle and plan appropriately at -viewDidLoad time. As for true image drawing, subclass UIToolbar and override -drawRect: and use [UIImage drawInRect:rect];