Null when printing boolean values

[chicagosky]

Hello

Please see code and output below. Can someone please help me understand :

1. Why I am printing out 'null' instead of the actual boolean values?

2. What format specifier should I use to print out boolean values?

    for (NSObject *itr in array) {
        NSLog(@"Class name: '%@'", [itr className]);
        NSLog(@"Is member of NSString: %@", [[itr class] isMemberOfClass:[NSString class]]);
        NSLog(@"Is kind of NSString: %@", [[itr class] isKindOfClass:[NSString class]]);
        NSLog(@"Responds to lowercaseString: %@", [[itr class] respondsToSelector:@selector(lowercaseString)]);
     }

2011-03-26 11:10:07.453 WhatATool[69348:903] Class name: 'NSCFString'
2011-03-26 11:10:07.453 WhatATool[69348:903] Is member of NSString: (null)
2011-03-26 11:10:07.453 WhatATool[69348:903] Is kind of NSString: (null)
2011-03-26 11:10:07.454 WhatATool[69348:903] Responds to lowercaseString: (null)

[smasher]

The format specifier %@ is only for objects; it causes NSLog to print the description of the object by calling the description method.

A BOOL is not an object, so you should not use that format specifier for BOOLs. Try using %d instead to get 0 or 1.

[chicagosky]

Thank You very much for the speedy reply. It helped to understand the format specifier. I also googled around and found this piece of code that works when wanting to print a string translation of the boolean value

        NSLog(@"Is member of NSString: %@", [itr isMemberOfClass:[NSString class]] ? @"YES" : @"NO");
        NSLog(@"Is kind of NSString: %@", [itr isKindOfClass:[NSString class]] ? @"YES" : @"NO");
        NSLog(@"Responds to lowercaseString: %@", [itr respondsToSelector:@selector(lowercaseString)] ? @"YES" : @"NO");

Case closed!