Programming Pitfalls: Bit in the ARC

Apple’s ARC (automatic reference counting) for Mac and iOS devices is intended to make Cocoa development easier. For the most part it does. However, in using it I have encountered a bit of a pitfall: by default the compiler does not optimize your code in debugging but uses its most optimized setting for release.  What does this mean? Well, the more you tell it to optimize your code, the sooner it will release objects for you, which can lead to some issues. To be clear the default settings for each mode are zero optimization and the most possible optimization respectively.

Basically,  a lib I was using was working fine in testing but was throwing BAD_ACCESS errors when running in release mode. After over an hour and half of investigating I found:

The screenshot is showing XCode’s “Build Settings” screen, where you can clearly see that a different level of optimization is being used for the two different modes.

From here the fix is pretty easy: tune down that optimization level. Alternatively, you could dig into the code that is having the issues, but that might turn out to be something of a premature optimization for most needs.

Hope this helps someone. You can find me on Twitter or Google Plus.

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