Under the Bridge

Extracting SDK icons

So as you’ve probably know already if you’ve tried to customize UITabBarItems, the images you provide are used only to extract the alpha channel. That makes usual stock art not the most applicable, and if you’re as artistically challenged as trolls, you’re not too interested in trying to figure out how to draw that kind of thing yourself.

So the immediate idea is, no doubt, let’s use some of the icons of that type already present in the SDK. Besides saving us trouble, that contributes to a cohesive user experience, and who couldn’t be in favor of that? For example, let’s decide we would like to have a camera image on one of our tabs. So we dig through the simulator resources, which are found at

/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator2.0.sdk/System/Library

and we find one that looks like what we want, inside the above at

/PrivateFrameworks/PhotoLibrary.framework/CameraIcon.png 

But wait, it’s not quite that easy! All the allegedly PNG images in the simulator SDK are actually in Apple’s wacky iPhone variation of the PNG format, so we have to deal with that somehow. As it happens, some extra friendly fellow has put up an online converter to do so for us. That produces a standard PNG file that we can simply toss into our project, set in Interface Builder … and hey presto,
tabbar
a standards-consistent UITabBar!
[UPDATE: Or, on the other hand, using a camera icon for a camera-related function could actually in Apple's eyes turn out to be a big bundle of FAIL. So be careful with how you use these icons, kids!]
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