_Nullable -can have a nil value
-Nonnull -not expected to be nil
1 2 3 4 5 6 7 8 9 10 11 12 | @interface Book : NSObject@property (nonatomic, copy) NSString *title;@property (nonatomic) Person *author;@property (nonatomic) Person *editor;@property (nonatomic) int yearOfPublication;-(instancetype)initWithTitle:(NSString*)title author:(Person*)author year:(int)year;@end |
