What values should I use for iOS boolean states?

Question

It appears that in iOS I have a number of options that seem to fit for boolean values:

YES
NO
TRUE
FALSE
true
false

Which ones should I use

Answer 1

Actually there is no difference between YES, TRUE and true those all represent a true state represented by 1.

And NO, false, FALSE is represents a false state represented by 0.

You can also use:

BOOL aBool = 1;

which is equivalent to BOOL aBool = true; and BOOL aBool = TRUE; and BOOL aBool = YES;

But:

BOOL bBool = 7;
if (bBool)
{
    NSLog(@"bBool is YES!\n");
}
if (bBool != YES) {
    NSLog("bBool is not YES!\n");
}

Will output like:

b is YES!
b is not YES!

This is because direct comparison with YES will fail when the value of a BOOL type is a non-zero value other than 1.

Here is a nice article for you.