1@interface RootObject 2@end 3 4@interface BaseClass : RootObject 5@property(atomic, assign, readonly) int field; 6@end 7 8@interface BaseClass(Private) 9@property(atomic, assign, readwrite) int field; 10 11- (int)something; 12@end 13 14@implementation BaseClass 15- (int)something { 16 self.field = self.field + 1; 17 return self.field; 18} 19@end 20 21