Self-Learning XCode/Objective-C: 'static' doesn't seem to mean what I *think* it means - objective-c

Question

I'm working through examples in the book 'Visual Quick Start, Objective-C' by Holzner. I spend a lot of time with each example, getting the code debugged is the faster part, and then stepping through saying to myself why each line of code works, what each word in each line does and deciding why the author used one way of doing things versus another. Then I repeat the example with some story of my own. This seems to be a good way to move from being a structured programmer and to an oop-like one. It works with these examples because he just does one concept at a time. (I've worked part way through 2 other books and this idea did not work for me in those. Once I got confused by something, I just stayed confused. There were too many variables in the lengthier, more complex examples.)
In the current example (page 137), Holzner uses the word 'static'. I looked through examples in this book to decide what this word means. I also read the description in Bjarne Stroustrups' C++ Programming Language book (I understand that C++ and Objective-C are not exactly the same)
(Bjarne Stroustup p 145)
use a static variable as a memory,
instead of a global variable that 'might be accessed and corrupted by other functions'
Here is what I understand 'static' means as a result. I thought that meant that the value of a static variable would never change. I thought that meant it was like a constant value, that once you set it to 1 or 5 it couldn't be changed during that run.
But in this example piece of code, the value of the static variable does change. So I am really unclear on what 'static' means.
(Please ignore the 'followup question' I left commented in. I didn't want to change anything from my run, and risk creating a reading error
Thank you for any clues you can give me. I hope I didn't put too much detail into this question.
Laurel
.....
Program loaded.
run
[Switching to process 2769]
Running…
The class count is 1
The class count is 2
Debugger stopped.
Program exited with status value:0.
.....
//
// main.m
// Using Constructors with Inheritance
//Quick Start Objective C page 137
//
#include <stdio.h>
#include <Foundation/Foundation.h>
#interface TheClass : NSObject
// FOLLOWUP QUESTION - IN last version of contructors we did ivars like this
//{
// int number;
//}
// Here no curly braces. I THINK because here we are using 'static' and/or maybe cuz keyword?
// or because in original we had methods and here we are just using inheirted methods
// And static is more long-lasting retention 'wise than the other method
// * * *
// Reminder on use of 'static' (Bjarne Stroustup p 145)
// use a static variable as a memory,
// instead of a global variable that 'might be accessed and corrupted by other functions'
static int count;
// remember that the + is a 'class method' that I can execute
// using just the class name, no object required (p 84. Quick Start, Holzner)
// So defining a class method 'getCount'
+(int) getCount;
#end
#implementation TheClass
-(TheClass*) init
{
self = [super init];
count++;
return self;
}
+(int) getCount
{
return count;
}
#end
// but since 'count' is static, how can it change it's value? It doeeessss....
int main (void) {
TheClass *tc1 = [TheClass new] ;
printf("The class count is %i\n", [TheClass getCount]);
TheClass *tc2 = [TheClass new] ;
printf("The class count is %i\n", [TheClass getCount]);
return 0;
}

Answer 1

"static" is not the same thing as C++ "const". Rather it's a statement that a variable be declared only once and is to remain (hence static) in memory. Say you have a function:
int getIndex()
{
static int index = 0;
++index;
return index;
}
In this case the "static" tells the compiler to retain the index value in memory. Everytime its accessed it is changed: 1,2,3,... .
Compare this to:
int getIndex()
{
int index = 0;
++index;
return index;
}
This will return the same value each time as the index variable is being created each time: 1,1,1,1,1,... .

Answer 2

To clarify No one in particular's answer even further, a variable that is static will remain the same throughout all instances of objects, between method calls, etc.
For instance, declaring the following method:
- (int)getNumber {
static int number = 0;
return ++number;
}
will return 1, 2, 3, 4, etc., across all instances of the given class at any given time. Neat, eh?

Answer 3

static means many things in C / C++ / Objective-C.
Objective-C follows C closely. In C++, static means more things than in C / Objective-C. So, don't judge what static does in Obj-C by what Bjarne Stroustrup says (who is the inventor of C++).
In C and Objective-C, two main meanings of static are
For a variable / function in the file level, it makes a variable / function invisible from other translation units (i.e. other source files compiled into the same program.) It doesn't mean its constant.
For a variable declared inside a function, it makes a variable not to reside in a stack but in a more persistent location, as explained by no one in particular.
In C++, in addition to this meaning, a static member in a class means it belongs to the class, not to an instance. This meaning is completely unrelated to the other meaning; in the olden days, people didn't want to introduce more reserved words in the language, so they just abused the same reserved words in different contexts to mean completely unrelated things. Another notorious example is the usage of the word virtual.
In any case, static doesn't mean it's constant.
Anyway, in a programming language, a thing means whatever the implementers or the standard committee members decide it to mean. Therefore I find it always helpful to read the standard. Just look for the word static in that PDF. You'll learn everything about static keyword in the programming language C there.