Is there a popular open source NSW replacement that only handles DEBUG and different log levels?

Is there a known / popular NSLog replacement / approach that many iPhone developers use?

Is it the one that only handles debug type logging in debug states (macros, etc.) and supports different levels of logs (DEBUG, WARN, INFO, ERROR, etc.)?

I understand that there may not be much work in implementing this, but I am curious to find out if there is a popular download that many iPhone developers are using that are already solving this problem.