Greetings! I must be seeing things. Look at this excerpt from the iPhone OS reference library:
addTimeInterval: Returns a new NSDate object that is set to a given number of seconds relative to the receiver. (Deprecated. This method has been replaced by dateByAddingTimeInterval:.)
However, it is nowhere to be found in the docs, nor in the headers. If I look at the Mac OS SDK, then I find it.
Typo? Just keep using addTimeInterval: after all??