Person model example

PersonModel.m

@interface PersonModel : NSObject

// Current person
@property(nonatomic, readonly) Person *person;

// Creates model for working with specified person
- (id)initWithPerson:(Person *)person;

// Follows current person
// Calls specified block.
// Result block can be called more than once
- (void)follow:(void (^)(Person *person, NSError *error))resultBlock;

// Unnfollows current person
// Calls specified block.
// Result block can be called more than once
- (void)unfollow:(void (^)(Person *person, NSError *error))resultBlock;

@end