objective C for loops

Well first of all the 'i' in a For loop is just acting as a counter, to understand this, recall what it is a For loop. In simple terms, a For loop is a loop or part of code that repeats again and again only if the condition is true (Boolean), and if the condition is false, the For loop will be ignored, passed.

So, the counter just acts as a counter for the condition to be tested. For example, in this program:

for (x=1;x<=10;x++) {
NSLog@("The value of X is %i", x);
}

This For loop what does is prints out the value of x 10 times. As you can see, the value of 1 is assigned to the variable x, and then the condition is what follows, and finally, the x++ (++ is the same as x=x+1). If the condition is true, the code inside { } will execute, if not, just ignored. Remember: after each iteration (that is, after each looping), the x++ will be called, that is after a loop (iteration), so take as an example that I'm the compiler when the program runs:

A For loop, ok Assigning 1 to the variable x If x<=10 is true, I will execute NSLog@("The value of X is %i", x); and after that, the x++ is what follows, then I will return at the beginning of the line to again, do a conditional test. If not, I will ignore that code and follow the program as normal.

So, in your question, instead of 'x' I think you are referring to a 'i', that's exactly the same thing, you maybe got a program that reads:

for (x=1;x<=10;i++) {
// code here ...
}

That is, that the variable 'i' is being declared outside the for loop, it's maybe a 5, or a 2, or 1, or 7, etc. That's perfectly valid in Objective-C.

Now, as I said before, the ++ after the variable (in this case, x) is called a Post-increment operator, that is, the same as x=x+1; and is used as a shortcut for the programmer, you can also use, a post-decrement operator, that is, x--, there are also, pre-increment and pre-decrement operator, but for now, stick with the post, that is the signs '++' and '--' AFTER (as POST) the variable. The PRE-increment is (++x) and PRE-decrement (--x).

They are all the same this will print the same results:

for(int y= 10; y==10; ++y){
//code here ...
}

than:

for (int y= 10; y==10; y++){
//code here ...
}

Hope I helped you! Comment me if you have any question, see you! =)