instance variable/ method argument naming in Objective C

Question

What conventions are people here following for naming of instance variables and method arguments - particularly when method arguments are used to set ivars (instance variabl

Answer 1

Obj-C does not define "style" as strictly as many other languages, this might be a good thing or rather a bad one, but it means you are on your own to find a good coding style most of the time.

You can also access variables in Obj-C via self. So if you have an instance variable test, you can access it via self->test, this is legit and will always work. It's not beautiful in the eyes of most Obj-C programmers, though. It gives away the "secret", that objects are in fact just structs (more precisely, object refs are pointers to structs) and instance vars are in fact struct members. Not that this is really secret, but Obj-C programmers seems to prefer to "hide" this fact in their code.

Using underscore "_" in the name is a very bad idea. Someone here pointed out that Apple reserves underscore for their code, but actually GCC already reserves underscore for symbol names. More precisely, already the ANSI-C standard says that variables starting with either two underscores or one underscore and an upper case letter are reserved for the compiler's internal usage. So using one underscore is in theory valid, but accidentally start the name with an upper case letter and it becomes invalid.

What I tried so far was using the prefix my, myName instead of name, and using the prefix self, selfName instead of name; looks both somehow strange at first, but doesn't look too bad in a huge piece of code. At least immediately hits the eye as being "different". I also just tried a single "i", iName instead of name (or iname instead of name), but I was not very satisfied with that solution.

I never wasted time thinking about method parameters, though. Because it does not really matter. Those are variables like any other variables, unless they are declared constant. They can be even re-used for other purposes within the method, because it will have no affect on the caller. E.g.

- (NSImage *)loadImage:(int)imageNumber
{
  NSImage * res;

  // Some code that assigns a value to res
  // ...  

  // Re-use imageNumber for a different purpose
  for (imageNumber = 0; ...; ...) {
     // Some code
  }

  return res;
}

I see no problem with that code. Why would I have to declare a second stack variable for that as long as the name still makes sense (if I'm not iterating over images by number in the for loop, the name makes no sense of course, in that case I would use a different variable for it - compiler may in fact reserve only one int on stack for both).