#define APP_NAME [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleName"]
#define APP_VERSION [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"]
#define OPEN_URL(urlString) [[NSWorkspace sharedWorkspace] openURL:[NSURL URLWithString:urlString]]

// Retrieving preference values
#define PREF_KEY_VALUE(x) [[[NSUserDefaultsController sharedUserDefaultsController] values] valueForKey:(x)]
#define PREF_KEY_BOOL(x) [(PREF_KEY_VALUE(x)) boolValue]
#define PREF_SET_KEY_VALUE(x, y) [[[NSUserDefaultsController sharedUserDefaultsController] values] setValue:(y) forKey:(x)]
#define PREF_OBSERVE_VALUE(x, y) [[NSUserDefaultsController sharedUserDefaultsController] addObserver:y forKeyPath:x options:NSKeyValueObservingOptionOld context:nil];

/* key, observer, object */
#define OB_OBSERVE_VALUE(x, y, z) [(z) addObserver:y forKeyPath:x options:NSKeyValueObservingOptionOld context:nil];

#ifdef __OBJC__
static inline BOOL isEmpty(id thing) {
    return thing == nil
	|| ([thing respondsToSelector:@selector(length)]
        && [(NSData *)thing length] == 0)
	|| ([thing respondsToSelector:@selector(count)]
        && [(NSArray *)thing count] == 0);
}
#endif

http://mabblog.com/source.html

Some macros that I use in many applications, provides an easy way to observe/retrieve preferences and access common application information

Useful Cocoa Macros

Objective C