How do you check for sanity in objective-c and cocoa?

Question

What is the preferred method of checking for sanity in objective-c and cocoa?

Answer 1

NSAssert(thisShouldBeTrue, @"Error message");

Answer 2

Near the top of a method, NSParameterAssert that necessary objects are not nil, indexes are in range, etc. Sometimes you can get these for free; for example, an indexed accessor backed by an array can let the underlying array do the asserting for it.