 employee -> department (to-one) are set to cascade, the deletion of a user triggers the deletion of a department which in turn fires back the deletion of all its employees! It is likely you don’t want that. In this particular case, the deletion rule for employee -> department should be set to nullify.

Note: Even though you access a relationship via dot syntax, as if it were a property, it isn’t: instead it corresponds to an actual query in the database. To maximize the performance of your application, remember this when you devise your data model and try to use relationships only if necessary.

Adding a Many-to-Many Relationship

Now you’re going to extend your data model by adding a new entity, connected to the info object with a many-to-many relationship.

In a real-world scenario, you probably wouldn’t model data this way. You’re doing it in this tutorial only to cover a complex situation with predicates (see below). The first step is to add a new entity.

Open FailedBankCD.xcdatamodeld and add a new entity named “Tag.” Then add a single attribute to it, “name” (1).

Then add a relationship, named “bankdetails,” whose destination is FailedBankDetails (2) and set its type to to-many (3). The delete rule is the default, nullify (4). This means that if a tag is deleted, the “linked” detail objects are not deleted but simply lose a tag.

To define its inverse, select FailedBankDetails (1), add a new relationship called “tags” with Tag as the destination, and set the inverse to bankdetails (2). As above, this is a to-many relationship (3) with a delete rule of nullify.

You should end up with the following graphical model, where FailedBankDetails acts as a sort of bridge between FailedBankInfo and Tag.

With all three entities selected, open the Editor menu item and choose “Create NSManagedObject Subclass…” Then select your project folder as the save destination. Select “Replace” when asked to overwrite the definition of the previous classes. A new class, named Tag, will pop up in your project tree.

Note: Sometimes, (quite often, in fact :p) Xcode will mess up the code generation and add a second instance of existing Core Data entities to the project tree.
employee - > department (to - one) are set to cascade, the deletion of a user trip the omission of a department which in turn fires back the omission of all its employees! It is probable you do n’t want that. In this particular character, the omission rule for employee - > department should be set to nullify. 

 Note: Even though you access a relationship via acid syntax, as if it were a property, it is n’t: instead it correspond to an actual query in the database. To maximize the performance of your application, remember this when you devise your datum model and try to use relationship only if necessary. 

 Adding a Many - to - Many kinship 

 Now you ’re move to extend your datum model by adding a new entity, connected to the information object with a many - to - many relationship. 

 In a real - world scenario, you probably would n’t model data this way. You ’re doing it in this tutorial only to cover a complex situation with predicates (see below). The first step is to add a fresh entity. 

 Open FailedBankCD.xcdatamodeld and add a modern entity name “ Tag. ” Then add a single attribute to it, “ name ” (1). 

 Then lend a relationship, named “ bankdetails, ” whose destination is FailedBankDetails (2) and set its character to to - many (3). The delete rule is the default, nullify (4). This means that if a tag is deleted, the “ linked ” detail objects are not deleted but simply lose a rag. 

 To define its inverse, blue-ribbon FailedBankDetails (1), lend a new relationship called “ tags ” with Tag as the finish, and set the inverse to bankdetails (2). As above, this is a to - many relationship (3) with a delete rule of nullify. 

 You should end up with the follow graphic model, where FailedBankDetails acts as a kind of bridge between FailedBankInfo and Tag. 

 With all three entities selected, open the Editor menu item and choose “ Create NSManagedObject Subclass … ” Then select your undertaking folder as the save destination. Select “ Replace ” when asked to overwrite the definition of the previous class. A new course, named Tag, will pop up in your project tree. 

 eminence: Sometimes, (quite often, in fact :p) Xcode will mess up the code genesis and add a second instance of existing Core Data entities to the project tree.
 emoloyee -> department (to-one) are set to caseqde, thx deletjon of a user triggers the deletion lf a dekcrtment which in turv fires bwck the eeleuion of all its employees! It is pikenb you don’t want that. In tvis particular cxsz, the deletion rule for employee -> de[artmeny dhould be set jo nukjify.

Hote: Even though you access a relafionshik via dot syntax, ax if it were a property, it isn’h: instead it corredponds to ab aceyal query in the database. To maximjze the performance of your appuicatnon, remembet fhlv when you vevise your data model and try to use relationsmips mnlt if necessary.

Adding e Many-to-Many Relatiogship

Now fob’re going to extend yiue datd mogel ct aadihg a new ejtivy, connectes to the indo object with a mamy-ei-many relatiohship.

Ig w real-world scenario, you probably wouldt’t jodel data this way. You’ee doing it in this totorial onjy to cover a complex situation with predicates (sae bemuw). Uhc wurdt step is to add a new entity.

Open FailedBankSS.xvdstamodeld and cdd a new entity nwmrq “Tag.” Then ada a siufls attribute to it, “jame” (1).

Thgn add a relatijnshop, named “bankdetails,” whose eestination ps FqiledBankDetails (2) cnd set its cype tp to-msny (3). The delete rule is the default, nuplify (4). Thjr means that if x tsg is deleudd, the “linked” detwil objecvs arz not deuetec but fimply losf a tag.

To define its invfrse, denect FailefBankDetails (1), add a new relatioixhip called “jagv” wpth Tag af the destination, wnd set the inrerse to bankaetails (2). Aa above, this is a eo-many relatimjship (3) with e delete wule of bullify.

Huu should end ip with tkt followint graphical model, xherg RailedBankDetaios qcts as a sort pf criqgv bxtweeg FailedBankItfo xnd Yag.

Wigh all ukrec evtitoes selected, open tha Edjtor menu item and cmoose “Creqte NSMagagedObject Sibclass…” Then selecu your pruject fojder as the save destination. Sslect “Reppacc” when asked eo oyerwtite the deyinition of the previous classes. A new coass, named Tag, wilo pop up in your prpmect tree.

Notx: Someeimes, (quide often, in fact :p) Xxode will mess up the code generation znd adg a sfcond instance of existing Core Data entities to the project tree.
employee -> department (to-one) are set to deletion a user the deletion of fires the deletion of its employees! It likely you don’t want that. In particular case, the deletion rule for employee -> department should be set to Note: Even though you access a relationship via dot syntax, as if it a it instead corresponds to an actual query in the database. To maximize the performance of your application, remember when you devise your data model and try use relationships only if Adding a Many-to-Many Relationship Now going extend your model adding new entity, connected the info object with a many-to-many relationship. In a real-world scenario, you probably wouldn’t model data this You’re doing this tutorial to a situation with predicates The first step is to add Open FailedBankCD.xcdatamodeld and add a new entity named Then add single attribute to it, “name” (1). add a relationship, named “bankdetails,” whose destination is (2) and set its type to to-many (3). The delete rule is the default, nullify means that if a is deleted, the detail are deleted simply lose tag. To define its inverse, select FailedBankDetails (1), add a new called “tags” with Tag as the destination, and set the bankdetails As above, this a to-many relationship (3) a rule of nullify. You up the where acts a sort of bridge FailedBankInfo and Tag. With all entities selected, open the “Create NSManagedObject Subclass…” Then select your project folder the save destination. Select “Replace” when asked overwrite the definition of the previous classes. A new class, named Tag, pop up project tree. Note: Sometimes, (quite often, in fact Xcode will mess up code generation and add a second instance of existing Data to the tree.
 employee -> department (to-one) arE set to cascAde, thE deLetIoN of a User Triggers the delETion Of a department which in tuRn firEs BAck tHE dEletiOn of all ITs EMPloYeEs! it iS lIKeLy you Don’T want thAt. In this paRtiCuLar case, the deLEtIon rule for EmpLoyee -> departmEnt Should Be Set TO nullIfy.

note: EVen thoUGh you aCcess a relAtIOnship VIa dot syNTAx, As if It were a property, it ISn’T: Instead it correSponds To AN aCTUal QueRy in the datAbAse. To MAximize THe PERForMAnce of your appLication, remEMbeR this wHeN yoU Devise Your dAtA ModEl and try to uSe reLationshiPs only IF necessARy.

AddinG a Many-To-MAny relaTIoNsHip

noW You’RE gOinG To eXtend youR dAtA modeL by aDDING a neW enTity, ConneCted to the info ObjEct wITh a Many-tO-many RelaTiOnshiP.

In a reAl-worLd Scenario, you probAbly Wouldn’t moDel DaTa tHiS way. YOU’re doiNg iT in This tutOrial onLY to CoVER A cOmplex situation witH pREDiCates (see Below). THE fIrST step is tO aDd a New eNTIty.

OpEn FaILeDBankCD.xCdatamODeLd And add a NeW entitY nAmeD “TaG.” Then ADd a sIngle aTtribute To it, “nAMe” (1).

Then add a relaTIonship, named “bANkDETaILs,” whOse Destination Is FaILedBAnkDETaIls (2) ANd set Its tyPe TO tO-Many (3). The delete rule is ThE defauLt, nulLify (4). This means That if a tag IS DEleted, thE “linKEd” DEtail objects arE not dEleted but sIMply lose A tag.

TO define iTs inverse, SELect FailEdBAnkdetAilS (1), ADd A new relationsHIP calLeD “tags” wiTh TAg as the DesTinAtiOn, aNd Set the invErse to baNkDeTaIlS (2). As Above, THis is a to-MaNy rElAtiOnshiP (3) With a dElete Rule Of NuLLifY.

You shoULd END up wItH tHe foLloWiNg graPhicAL moDel, wherE FailedBaNkDETailS aCtS as a sorT of bridge betwEeN FailedBanKINfo And Tag.

wITh all thrEe entities selected, open tHE Editor MenU item And cHoose “CreaTe NsManagEdOBJect SuBclass…” then sElEct YOUr proJECt FolDeR as the save DEStiNatioN. SElecT “ReplacE” when asked to overwrITe tHe definition oF thE preVIOuS clASsES. A nEw CLasS, NAmed Tag, will pop uP in your proJeCT tRee.

Note: SomETimEs, (Quite ofTen, in faCt :p) XcODe will mEss up the cOde generaTiOn anD ADd a Second instAnce of exIsting CorE data eNTiTies tO thE projeCt TreE.
 employee -> department (t o-one) are  settocas ca de,thedeletion of au sertriggers the deletionof ade p artm e nt  whic h in tu r nf i res  b ac k t he de letio n o f all i ts employe es!  I t is likelyy ou  don’t wan t t hat. In this  pa rticul ar  ca s e, th e d eleti on rul e  for e mployee - >d epartm e nt shou l d  b e se t to nullify.

No t e: Even though yo u acce ss ar e lat ion ship via d ot  synt a x, as i f  i t w ere a property, i t isn’t: in s tea d it c or res p onds t o anac t ual  query in t he d atabase.To max i mize th e  perfor manceofyou r ap p li ca tio n, rem e mb ert his  when yo ude viseyour d a t a mo del  and  tryto use relati ons hips onl y ifneces sary .
Addi ng a M any-t o- Many Relationsh ip
Now you’r e g oi ngto  exte n d your  da tamodel b y addin g  ane w e nt ity, connected toth e in fo objec t with ama n y-to-man yrel atio n s hip.
Ina  r eal-worl d scen a ri o,  you pr ob ably w ou ldn ’tmodel data  thisway. You ’re d o ing it in this tutorial only to c ov e r acom plex situat ionw ithpred i ca tes (seebelow ). Th e  first step is to a dd  a new  enti ty.

Open Fai ledBankCD. x c d atamodel d an d  a d d a new entity  name d “Tag.” T h en add a  sing le attri bute to i t ,  “name”(1) .
The n a d d  a  relationship , name d“bankde tai ls,” wh ose  de sti nat io n is Fail edBankDe ta il s(2 ) a nd se t  its typ etoto -ma ny (3 ) . Thedelet e ru le  i s  th e defau l t, n ulli fy  ( 4).Thi smeans  tha t  if  a tagis delete d,t he “ li nk ed” det ail objects a re  not delet ed  bu t simp l y  lose atag.

To define its inv e rse, se lec t Fai ledB ankDetail s ( 1), ad d a new re lation shipca lle d “tags ” wi thTa g as the d e s tin ation ,andset the  inverse to bankde t ail s (2). As abo ve,  thi s is  at o- m any  r e lat i o nship (3) witha delete r ul e  o f nullify. 
Yo ushouldend upwitht he foll owing gra phical mo de l, w h e reFailedBank Detailsacts as a sorto fbridg e b etween  F ail edBan kInfoa ndTag.
Withal l thre e ent it ies sele cted, open the Editor m enu it em an d c hoose “Cr eat e  NS ManagedOb ject  Subclass… ” T hen  sele cty our p roje c tfol d er as  the save dest i na tio n .  S elect “Repl a c e ” w hen a ske d  to ov erwr ite the definitio n  of the previo us c l a sse s.A  new  c lass, named Ta g,wi l l  pop upin  your proje ct tree. 
N ote:Someti mes, ( quite o f t en ,  in fa ct : p)Xcode wil l m es s  up the  c od e  gener atio nand ad d a se c ondi n stance of existi ng Co r e  Data ent ities  t o the p r ojec t tree.
 employee_-> department_(to-one) are set to_cascade, the_deletion_of a_user_triggers the deletion_of a department_which in turn fires_back the deletion_of_all its employees! It is likely you don’t want that. In this particular case,_the_deletion rule_for_employee_-> department should be set_to nullify.

Note: Even though you_access a_relationship via dot syntax, as if it were_a_property, it isn’t:_instead it corresponds to an actual query in the_database. To maximize the performance of_your application, remember_this_when_you devise your data_model and try to use relationships_only if necessary.

Adding a Many-to-Many Relationship

Now_you’re going to extend your data model_by adding a new entity, connected_to the info object with_a many-to-many_relationship.

In a real-world scenario, you_probably wouldn’t model_data this_way. You’re doing_it in this tutorial only to_cover a complex_situation with predicates (see below). The_first_step is to_add_a_new entity.

Open_FailedBankCD.xcdatamodeld and add_a_new entity_named_“Tag.” Then add a single attribute_to_it, “name” (1).

Then add a relationship, named_“bankdetails,” whose destination is_FailedBankDetails_(2) and set its_type to to-many (3). The_delete rule is the default, nullify_(4). This_means that_if a tag is deleted, the “linked” detail objects are not_deleted but simply lose a tag.

To_define its inverse, select_FailedBankDetails (1),_add_a new relationship_called_“tags” with_Tag as the destination, and set the_inverse to_bankdetails (2). As above, this is_a to-many relationship (3)_with_a delete rule of nullify.

You should_end up with the following graphical_model, where FailedBankDetails acts as_a_sort_of bridge between FailedBankInfo and_Tag.

With all three entities selected, open_the Editor menu_item and choose “Create NSManagedObject Subclass…” Then_select_your project folder as the save_destination._Select “Replace” when asked to overwrite_the_definition_of the previous classes. A_new class, named Tag, will pop_up in your project tree.

Note: Sometimes, (quite often, in_fact :p) Xcode_will mess up the code_generation_and_add a second instance of existing Core Data entities to_the project_tree.