Ask a basis for comparison declaration syntax problem

Just beginning to learn, to see a statement like this below:
(Void) a: (xx) aaa bbb: (xx) ccc

Specific remember, please forgive ==
Ask you, what does it mean that bbb? Or am I wrong horse, there is no such thing ah.
As far as I understand it, if you do not have that bbb. Convert c language function is:

void a (xx aaa, xx ccc);

Bbb how to figure out in the end that is how it is, do not know how to check the contents.
Recently started to learn this in the future might know, but now look at this encounter, very anxious. The introductory chapters of the book are seeing it turned a few did not find answers to trouble you, thank you!
Reply:
(Void) a: (xx) aaa bbb: (xx) ccc
Equivalent
void abbb (xx aaa, xx ccc);
Reply:

cited a floor darkdong reply:

(void) a: (xx) aaa bbb: (xx) ccc
Equivalent
void abbb (xx aaa, xx ccc);

Thanks, but still somewhat puzzled.
Bbb ask here is what belongs to, what significance does this wording (this is true not understand)?
Reply:
bbb as a placeholder, nothing mysterious, is this format. LZ look even more basic.
Reply:
- (Void) setTire: (Tire *) tire
atindex: (int) index;

Also see a similar statement, or not very understanding.
Reply:
bbb is the second parameter's name, the name is generally the first parameter is omitted
For example, you now need to call this function, then write [self a: bbb:??]; Wherein A is a function name
Beginning not accustomed to long to get used to
Reply:
Now know what it means.
To see that the "Objective-c-based tutorial" no mentioned. And the translation really sucks, some Chinese, we should see a few know what it says. Looking angry.

Does anyone have any good introductory book objC can recommend ah.
Reply:
object c 2.0