objective c - Core Data prepareForDeletion woes -


i'm interested how preparefordeletion works.

i have pretty simple object graph. 1 class called individual , 1 class called group. relationship between them many-to-many.

what have done far when delete group, check if individuals belong group belong group being deleted, if delete individuals well.

it looks this:

group.m

- (void)preparefordeletion {      //individual check: if group last associated individual, delete individual     (individual *individual in self.individuals) {          if ([individual.groups count] == 1) {             [self.managedobjectcontext deleteobject:individual];         }     } }

now had idea same approach individual. is, when individual deleted check if individual deleted last 1 in group. if it's last individual group should deleted well.

individual.m

- (void)preparefordeletion {      // group check: if individual last associated group, delete group     (group *group in self.groups) {          if ([group.individuals count] == 1) {              [self.managedobjectcontext deleteobject:group];         }     } }

so if choose route delete individual has has 1 relationship 1 group. both individual , group should deleted:

individual *individualtodelete = ... [moc deleteobject:individualtodelete];

now in preparefordeletion in individual.m delete group (since has 1 individual) go preparefordeletion in group.m , there try delete group well? since has 1 individual?

to remedy should call save after calling delete, like:

- (void)preparefordeletion {      // group check: if individual last associated group, delete group     (group *group in self.groups) {          if ([group.individuals count] == 1) {              [self.managedobjectcontext deleteobject:group];             [self.managedobjectcontext save:nil];         }     } }


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