NSAssert

NSAssert can be disabled if NS_BLOCK_ASSERTIONS is defined.

Had a nasty bug recently where some third-party code had critical statements in an NSAssert statement (a big mistake in any language), and NSAsserts had been disabled with a command line parameter unbeknownst to me in the project. Until then, I had never seen a case with NSAssert disabled.

Same code worked in another project in release, but not in this one. Fiendishly hard to track down.

I disagree entirely with the suggestions in this post, but it helped me track down the issue by pointing me to NS_BLOCK_ASSERTIONS.