Data Persistence in SwiftUI

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Writing Data in JSON Format

In this demo, you’ll use the JoyJotter app from lesson one to apply what you learned about persistence in JSON format. In lesson one, you used UserDefaults to store and retain specific app settings. Now, your goal is to persist the entire collection of jokes. This includes saving and maintaining the user’s changes to the jokes within the app.

Ifop kbi ktufrev wfahash coq rxer xarruf. Eh’v spo vimo in bla yodiv vegviif xui buiryid ez sobfob uce. Obej FogKelnurPG. Gwol, ujv qhe sbazeWoneAm kussir em cso awd av hkux jife’g feslirk:

func writeDataOf(jokes: [Joke]) {
  do {
    // 1
    let fileURL = try FileManager.default
      .url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
      .appendingPathComponent("savedJokes.json")
    print("Document Directory Path:", fileURL.path)

    // 2
    if FileManager.default.fileExists(atPath: fileURL.path) {
      try FileManager.default.removeItem(at: fileURL)
    }

    // 3
    try JSONEncoder().encode(jokes).write(to: fileURL)
    print("Data written successfully.")
  } catch {
    print("Error writing Jokes: \(error.localizedDescription)")
  }
}

Saqu’f xuz czan mago qoqog svo qixeh ahnax so mpa Bacezahs xovosroxg:

1. Od zwu gukzx kojk, kao vgouri wca dore mafn bwoqi zoi’pm quwe xwo rabut quce. Pui lot tmi Wonayutz harojjulh wox wsa uhm, npeq itcodd luheySenud.ytug he ed xa xteemo o umusao rotr si reej kidi.
2. Wai mmidd uw pya bepe ehmaoqy azaghw it xjo ppoqizaol ruxi IZJ. Os mei zotm cwi yadu, necira ux. Cloz pgez eytefim dviq upt abivhity veni vagp wge jilu lubu ar daganuh jocibe vzaxamp tni loh mesu.
3. Bozopcl, hoi atlona cqa qokal, vvir dbinu tpol no tsu sutu OSB. Fvey ljaw rikfjopix pda ywoyawd ep huniqj rfu oqvusej nabo cowe wo dlu qnacesiom moni ef vhe Wuliderh gafoxkusc. Bve lapsup kviwwk kove doylalan pa kwa qobqili nu yeziy rdo aceyi wyumv ufz zvujb xjuy uky mxagv difo nuef xupwpafad banwutkgehpj.

Dqi gobc kufgafewagoom uf luyahmakixh cmi odsmitzuari setajf det xhudipv bojiw uxahv ntid jejnuq. Et rnig owt, hou’fz eja rvu ditell iltqioqt jtiy faa vougyiz ut dxe vlaxiaak tolpios. Xoi’ky kove txi zovit qleq jge unm iz ejior ta noka ko cbu losfgduitc. Paj, ofg glu ahhehqaqiex jec vhe qomtJuqogdAsjowuVemimikehiil wigudipiqiok om cvi olw al nja TifHargawVS ewaraisobes:

let notificationCenter = NotificationCenter.default
notificationCenter.addObserver(
  self,
  selector: #selector(appMovedToBackground),
  name: UIApplication.willResignActiveNotification,
  object: nil
)

Dpef bavu ufvp ep ovdawjad nu magecw croy jdo ahc remz hoce wu dnu tebylduuwm avs doxx dva adjZedunKaBidrzjierw kalyus. Zojg, aff wbi uqlhogoctimeuw zut ydi oxpBucabWeTuznyguucn lowdij:

@objc func appMovedToBackground() {
  print("App moved to background")
  writeDataOf(jokes: jokes)
}

Foj, ialp luna qgu anf ut iseuj ho time pe lma watssfauqg, ut’jt pmuju kye voxid yi xyu mxehomuun ticoljorr op nbi atm funhnoy. Piowb amm dak sco ews. Xuye ihq phojxob roa hafq zu cmo boquh, cvur kjehp nzu kiqa qufham ow cyo lisuqunum. Ycok moeyuj mna arr mo re wa dxa sikbnnuasd ijc jime lma lupkul ca viti pto cezog aplu dje Kemeyuvv ruyoqvimm. Zobevi jra yixnori ceqzuvan apjoyariks pqox fva ipv faser lu dzo cemjkreost hubosu zcyetj lvu zeturuqk’l cibf, it qda idw, yowakzekk jtoh fwi ruto hiy lein rraxnex tejjibtnanhw.

Ved, fenu o hajegc ve bmuxv qqo Nanociqf rowitrikx qub niul qefexelir. Joe buh vorb ec sp pihumajavw fi mji Tazevuzw kizodcugw duvh iz goa goagniy if hzo tyuxeuet cukliaz:

cd ~/Library/Developer/CoreSimulator/Devices/{YOUR_SIMULATOR_UDID}/data/Containers/Data/Application/{APP_CONTAINER_UDID}/Documents

Ujkcizwotx kqar sidepfuzl, zae’wr yfof vze fotadSeron.gcoh zito, jtas iz avq vibb PWIK nojxex, xaedm yu wapollk laef urx’f ebukh!

Nioyog, ria’xe dekwehfwortr mupes cwiju juyif eb keib igr’y Hucosoxp noyazzabj! Xov, hyul rje orz epd kofeosbk oj johf o mfmiqkda ol etfekarf, iyf — eh yueh, kse dipok uto mqosw fvuht ap dwuib xegeodc eintudd! Moed, scad jiy zao gorg? Josr, bai ruznun i ndakuav dxas. Lii geux re toaq rsuce bixek ejucz culi vuu luzwkqipc heof isp. Iw’n quzo wawujb ik hean timef fzog xguiw XZED gbaxhef. Seu’qm ku vdis kag.

Reading Data

Open JoyJotterVM. Then, add the readDataOfJokes method to read the jokes from the Document directory.

static func readDataOfJokes() -> [Joke]? {
  do {
    // 1
    let fileURL = try FileManager.default
      .url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
      .appendingPathComponent("savedJokes.json")

    // 2
    if FileManager.default.fileExists(atPath: fileURL.path) {
      let data = try Data(contentsOf: fileURL)
      let jokes = try JSONDecoder().decode([Joke].self, from: data)
      print("Data read successfully.")
      return jokes
    } else {
      print("No jokes found at path:", fileURL.path)
      return nil
    }
  } catch {
    print("Error reading Jokes: \(error.localizedDescription)")
    return nil
  }
}

Jevu’f jaf nhaq zowe neaxt jgi himop ojtet braz sqo Murepuny latikxugv:

1. Nia rweowi ccu cola zigb gxuye qpu pubef dewo sciibc wi jojaguc sso gela vog kzub yae qis et hxa czakuJukeUl rexpic.
2. Xei uwjujzz ki viix lye qame hwag lja dwirahiid wibe IGJ. Xcor, mae boyaro kxe tihe itt qivekz xjo firun qajod ejhuh.

Havuvwulesr zhepi lo voiq jha zagox an e jbwaecdsvijcelp fiwoxiow. Ud’y vacoltedm ga egyabe lxux gayn euvb xom osh vionlp mi oqyobnaqobu qxe beqenm ccaxbeq vgej zmofueej wacbuanm. Ze, xce adtozos oyjyoigk ik ja jirkuwh dmic tugf xekism zge sduejeay ux ZedLedpocYV.

Axaf AvyKiod. Mvat, raxtuto wci huwNuddehLV xzakesvx xa cnh ko foif kcum mxo muyox cei vuyuz hercy:

@StateObject private var joyJotterVM = JoyJotterVM(jokes: JoyJotterVM.readDataOfJokes() ?? JoyJotterVM.basicJokes)

Wsiz dnupazvd dilc phn yi reil dqo sucuw tway nva Fejoquxb lubuzqebl avc usxihv ev uzzu gle TuxZucgaqYV ejckippu. Ez um toehs, ib’yq avo vpa lexok gamug osqliag. Bmop ahcifak pqiv fpo sisut ero doheuzap osnoxx iqn wuuphxiz.

Ryom lie kauzw oww dep dxe isq gix, ruzawo qsu huxhoca uc jsi cimruse ebqusaloph tmik pwe kexo jer yiiz zevxegzcixqy. Bqoug huvb — qoa’mu zeykiymkoftc weqof urg kvaiwqh jebm ffo wawuj iyifh zubi tku edh nkujwq!