categories - Objective-C: Should I declare private methods?

Question

I've been declaring private methods in class extensions, according to Best way to define private methods for a class in Objective-C.

But, I just realized that, in Xcode 4, if I leave out the declaration of a private method altogether and just implement it, the app compiles and runs without warning or error.

So, should I even bother declaring private methods in class extensions?

Why should we have to declare methods anyway? In Java, you don't... neither in Ruby.

Answer 1

A method definition only needs to be defined if the caller is declared before the method. For consistency I would recommend defining your private methods in the extension.

-(void)somemethod
{
}

-(void)callermethod
{
    //No warning because somemethod was implemented already
    [self somemethod];
}

-(void)callermethod2
{
    //Warning here if somemethod2 is not defined in the header or some extension
    [self somemethod2];
}

-(void)somemethod2
{
}