Related Object Lookup Pattern

gistfile1.m

@interface Person

// Derived from JSON
@property (readonly) NSString *personID;
@property (readonly) NSString *name;
…

@end

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@interface Company

// Set on object creation
@property (readonly, weak) PersonManager *personManager;

// Derived from JSON
@property (readonly) NSString *companyID;
@property (readonly) NSString *generalManagerPersonID;

// Convenience Methods
@property (readonly) Person *generalManager; // returns [self.personManager personForPersonID:self.generalManagerPersonID];

@end

////////////////////////////////////////

@interface PersonManager

@property (readonly) NSArray *persons;

// Initially, this will be a naive linear-search, requiring no extra state or configuration.
// If it turns out to be a performance hotspot, these query methods can be optimised by
// adding an NSDictionary cache (keyed by Person.personID), which will speed up all model-relation
// lookups that use the given method.
- (Person *)personForPersonID:(NSString *)personID;

@end