ios - How do you access NSManagedObjects between blocks? -

like title says how 1 go accessing nsmanagedobject has been created in 1 block , needs accessed in other. have following implementation , wondering if it's correct.

__block person *newperson;  @weakify(self); [magicalrecord savewithblock:^(nsmanagedobjectcontext *localcontext) {      newperson = [person mr_createincontext:localcontext];     newperson.name = @"bob";  } completion:^(bool success, nserror *error) {     @strongify(self);     // called on main thread      personviewcontroller *personvc = [[personviewcontroller alloc] initwithperson:newperson];     [self.navigationcontroller pushviewcontroller:personvc animated:yes];  }]; 

am correct in not needing access newperson localcontext in completion handler because it'll executed on main thread?

edit

it looks following proposed way:

__block nsmanagedobjectid *newpersonobjectid;  @weakify(self); [magicalrecord savewithblock:^(nsmanagedobjectcontext *localcontext) {      person *newperson = [person mr_createincontext:localcontext];     newperson.name = @"bob";     newpersonobjectid = newperson.objectid;  } completion:^(bool success, nserror *error) {     @strongify(self);     // called on main thread      person *savedperson = [[nsmanagedobjectcontext mr_defaultcontext] objectwithid:newpersonobjectid];      personviewcontroller *personvc = [[personviewcontroller alloc] initwithperson:savedperson];     [self.navigationcontroller pushviewcontroller:personvc animated:yes];  }]; 

solution

this answer , comments lead following solution. temporaryid being assigned object whilst it's being saved , therefore when trying fetch object tempid exception occurs.

rather creating whole new fetch request can done asking context obtain permanent ids , acquiring permanent id of object. example:

__block nsmanagedobjectid *newpersonobjectid;  @weakify(self); [magicalrecord savewithblock:^(nsmanagedobjectcontext *localcontext) {      person *newperson = [person mr_createincontext:localcontext];     newperson.name = @"bob";      [localcontext obtainpermanentidsforobjects:@[newperson] error:null];      newpersonobjectid = newperson.objectid;  } completion:^(bool success, nserror *error) {     @strongify(self);     // called on main thread      person *savedperson = [[nsmanagedobjectcontext mr_defaultcontext] objectwithid:newpersonobjectid];      personviewcontroller *personvc = [[personviewcontroller alloc] initwithperson:savedperson];     [self.navigationcontroller pushviewcontroller:personvc animated:yes];  }]; 

you can't directly pass managed objects between contexts. each nsmanagedobject can accessed own context.

you'll need pass objectid completion block, have main context fetch object calling 1 of following methods:

-(nsmanagedobject *)objectwithid:(nsmanagedobjectid *)objectid 

this create fault object specified objectid, whether or not exists in store. if doesn't exist, fires fault fail exception.

-(nsmanagedobject *)existingobjectwithid:(nsmanagedobjectid *)objectid                                    error:(nserror **)error 

this fetch object store has id, or return nil if doesn't exist. unlike objectwithid, object won't faulted; attributes have been retrieved.

in either case, local context must have saved person object store main context able fetch it.

more details objectid can found in core data programming guide

edit user asking question

this answer , comments lead correct solution. temporaryid being assigned object whilst it's being saved , therefore when trying fetch object tempid exception occurs.

rather creating whole new fetch request can done asking context obtain permanent ids , acquiring permanent id of object. example:

__block nsmanagedobjectid *newpersonobjectid;  @weakify(self); [magicalrecord savewithblock:^(nsmanagedobjectcontext *localcontext) {      person *newperson = [person mr_createincontext:localcontext];     newperson.name = @"bob";      [localcontext obtainpermanentidsforobjects:@[newperson] error:null];      newpersonobjectid = newperson.objectid;  } completion:^(bool success, nserror *error) {     @strongify(self);     // called on main thread      person *savedperson = [[nsmanagedobjectcontext mr_defaultcontext] objectwithid:newpersonobjectid];      personviewcontroller *personvc = [[personviewcontroller alloc] initwithperson:savedperson];     [self.navigationcontroller pushviewcontroller:personvc animated:yes];  }];