Explain why NSURL throws errors on nil

Question

Most to all of the classes in Objective-C returns nil if passed nil or some error, but NSURL throws an exception. Specifically, the method [NSURL fileURLWithPath].

It is documented: "Passing nil for this parameter produces an exception."

But, can anyone explain Apple would throw an exception instead of returning nil?

Answer 1

It is calling a method on nil that is allowed. Many methods can throw exceptions if given an invalid argument. For example see NSMutableArray's addObject:.