Question

How do I make a tab bar transparent in cocoa touch?

Answer 1

Since UITabBar is a subclass of UIView, have you tried adjusting its alpha property?

Note that if you are trying to modify a tab bar associated with a UITabBarController, you should consider this warning from Apple, located in the reference for UITabBar:

Important: In iOS 3.0 and later, you
should not attempt to use the methods
and properties of this class to modify
the tab bar when it is associated with
a tab bar controller object. Modifying
the tab bar in this way results in the
throwing of an exception. Instead, any
modifications to the tab bar or its
items should occur through the tab bar
controller interface. You may still
directly modify a tab bar object that
is not associated with a tab bar
controller.