Objective-C: Assertion vs. Exception vs. Error

Question

In Cocoa, when should I use NSAssert, NSException, NSError?

Here\'s what I\'ve been thinking:

NSAssert - When creating any client program us

Answer 1

In general, exceptions are used to signal programmer errors — they're things that shouldn't happen. Errors are used to signal error conditions that might come up in the normal operation of the program — user errors, basically, or external conditions that need to be true but might not be. So trying to delete some locked element in a document might be an error, and trying to download a file without an Internet connection would be an error, but trying to access an invalid element in a collection would be an exception.

Assertions are typically used in testing, and AFAIK are not used as a general error-handling mechanism like the others.