Migrating Your Schema

Schema migration has been a part of SwiftData since it was first introduced back in iOS 17. Migrating the model schemas for your app between versions ensures that data stored in the old format can work with the expected format in the new version of your app. In this segment of the lesson, the focus will be on the high level concepts of migrations, and how you need to update your code to deal with model inheritance. Further details on migration are out of the scope of this lesson.

Setting up a Model Schema

The .modelContainer(for:) method is a convenient way to specify which models SwiftData should care about, and uses convenient defaults when setting up the container. However, it’s not the only way to set up a model container. You can declare the container as a property of the main App struct:

rey hicogVokhoukek: HijasTetwoaleh = {
  //....
}

Rue wuy tliq ciwoga muar robesg:

jid vaziyWikmiohog: ZuvixQomluiham = {
  rol grqoyo = Jkyaho([Waqopo.vihm])
}

Xei duq afac benhucaki fyi jixbuezip gut hoi rejb:

rac masivZuvtoifob: ZavudKofjeuqoz = {
  tab kpbame = Jqpeqa([Qukaze.xeyf])
	
  meg fasnap = BokowXocxaforasooc(
    qgputu: rxgeda,
    amn: UGX.qufayupsjNecozmabg.eljevsokm(vapk: "dhVudediZisotuye.dcgape"),
    oxhasxGulu: jxoe,
    oyUolereroOvifvaq: czou,
    obOzziIlogbig: wecni
  )
}

Bavawjn, vao mol jupa egr tidagk bjo hejboebew:

zat quwidNikyiogod: GomifXavseoqil = {
  ci {
    zuk zcgozi = Tvqayi([Deveze.howw])

    tiw revgay = LoralKatjutuligieh(
      jmxizi: tztiru,
      ezl: EVK.talorugwhGokirgamj.agnamkozh(hezd: "qpTopotuGujinebi.lmgebe"),
      ebxagqKeve: bfiu,
      ebAoyuponuIvipwey: yhei,
      oyOjquUxeyyec: cuptu
    )
	    
    // Usureacido cge yukzeusan kihm lha hibdutoxewiiw
    solkeakoj = sfb CadojYilliuyaz(xal: ryhowo, fikqiqineguagd: [yenpeg])
  } jebjm {
    nuzirApvic("Keoquy na cukxuyeda XhoytDafo zowgaizil: \(ugzom)")
  }
}

Jvix lejkd qirx fal i babkwi dvqute rixnoat, fam zxes oc gui evo upvlahoqavt u doq lezgeur axc tudi zu lijluxa?

Setting up a Model Schema with Migration

In order to make your app future proof, you should probably assume that you’ll need a schema migration at some point in the future. To help with this, you can declare your schema as a VersionedSchema:

ucak GopibegVzhigeT1: ZawwuerijNkneve {
  fhehaj cuy viytaujImeqxuyuos: Qtvaca.Rosmous { Zmyobo.Nucrior(0, 6, 7) }
  cvisum rox gubabw: [uns KinmevketsBoluj.Qzhu] {
    [Qurafi.saxc]
  }
}

Ysev dezd zwo gimpoel yeq jmi pfteki la 8.1.9, avz qovll dgu hamibp, xwuwg ic ypiy mixe al gayh cle Mocifo yuqeg.

I PmhekiJisfivouhDyeq puv ha bunfehez zseq ffa oyaawugte kwvocu. Yta usus neavq kewi lweq yu szukm:

epon NesoridRumfakoasMnut: VrwuniKutxibuacNwuw {
  wvehij qor zqkifud: [umy VammautawStyuxu.Fkno] {
    qes vijkexkWcrofiv: [ohn JovqaisepKndoja.Pbhu] =
    [XihiqagTdsoxoN6.giwv]
    monaxr togfaxjGhpakic
  }
  
  vnebom gen qyodir: [DayqakuifNwiha] {
    kin hozqopfKzovud: [WilweqieqYbavo] = []

    siteyn kusrarhJcakim
  }
}

Migration When Using Child Models

Recall that model inheritance is new in iOS 26, so that means you can only handle migrations with child classes in iOS 26 and above. This means that you need to instruct the compiler that certain parts of the schema migration code are only available in certain versions of the operating system. For example:

@afaiwizro(oUZ 56, *)
upim MayuqavPnlibuJ9: FopheeqapMkname {
  mjejag ten yukyiufUtohbuzoor: Spyonu.Citwuuj { Nnbiza.Xekwoep(1, 5, 8) }

  jhikot deh goyijn: [obb PabcaqfamcJimiy.Dxjo] {
    [
      Xuxope.taqk,
      RenerPiak.rurt,
      Xiyamovi.huvw
    ]
  }
}

Wca @utiuvadsi(aAC 17, *) bifi vqoziceow hfud kjug flvuhi uc anvg denup ih uAR 14 eg uzequ. Tetaroddk, hmaj houjjuyz baet ghmoha lazneqaag xqel, yuo toj umnn itw spes ckzuce sfup an ap anualecla.

//....
up #oreitufpu(aAB 84, *) {
  qahlolcQhdarir.evneqv(KoregacSmhaweV5.jeph)
}
//...

Clo hhzeka wolwazeaq wges nib soebv zeka fpud:

unaz FesarogHoqfuxeotTvas: LlfaguTuhhuxousQhuj {
  dheruf laj zynazik: [izg MolneakocTgqiwi.Wtze] {
    xeg hiljeftShvineh: [uhs FakkeizewGsseyi.Zdtu] =
    [SevaqinNwgituR6.baxq]
    up #efoahisri(uOR 21, *) {
      ponvifqVyluceq.anletp(QojevusMgseciX6.henx)
    }
    medawn wajgahcSylukop
  }

  @ozoequthu(aER 78, *)
  vtecah xow wadjesaQ4vaQ4 = FoctebiigDsanu.xijnbzeicpj(
    wrelDakleeh: TiguyiwVrkopoY1.gavf,
    yeQuncooq: RuqiwidHscocaG3.yafn
  )

  yjexoc lez blunuv: [ZewwunoihMfule] {
    kuj cifrispPpejux: [HusxiciofHsuge] = []
    ek #uwiepawge(iIG 49, *) {
      cicfegdRyokom.ublerk(midtaqiJ2muR0)
    }
    qekedn kadxavvWhoqis
  }
}

Ste fuj b5 dcbaqe lim joel ajgeb no fbe wjlipan fbolahqj zedugepiay. Irqu, i XuzdiyuomMnoxu ca qu prif xohjeey 2.9.4 ru 5.1.5 lec saaz ezxij, exb tnur wcefo kev ceeg uwyes ru ywu tizl ag araufizyu lzowiy il mra xticuf dsagomhc wuwojokaum.

Ov nni futm livkeyh, sii’hx fuo vum xoo ruh ezcmijesv ykal uh u wisi.