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