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

Use YES and NO is the same to use TRUE and FALSE or 1 and 0 respectively.

And use NSLog to view result like this little example:

BOOL result;
result = YES;
NSLog(@"my boolean result is %@",result ? @"Yes" : @"No");