Constants.h

extern const struct DomainRelationships {
	__unsafe_unretained NSString *records;
	__unsafe_unretained NSString *registrant;
	__unsafe_unretained NSString *user;
} DomainRelationships;

Constants.m

const struct DomainRelationships DomainRelationships = {
	.records = @"records",
	.registrant = @"registrant",
	.user = @"user",
};