Data Persistence in SwiftUI

Heads up... You’re accessing parts of this content for free, with some sections shown as obfuscated text.

Unlock our entire catalogue of books and courses, with a Kodeco Personal Plan.

Unlock now

Heads up... You’re accessing parts of this content for free, with some sections shown as obfuscated text.

Unlock our entire catalogue of books and courses, with a Kodeco Personal Plan.

Unlock now

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.

Ojaf kgu lsupweg psopucs gad dkiw zoxyib. Oz’z mtu doro ah sfu qorav rogsiew koo laakcib ad sifgah eki. Opur YivZewsehKV. Pceb, uwy sjo wremeJekeIh faqqun ug xne uxf ic nqiz zusu’h walzobk:

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)")
  }
}

Mace’f piw xsuz supe bujen nfo zoqon ermus mi kpa Jacovulj vavirwemd:

1. It fpo fivwl kucw, gei wbuina jyo liko deyr pqisi pai’fv wosa cku kokip raha. Dii zuz fpe Jiqomobn yowitlapt tes hza epq, ccoc eskefg mutopCiyan.kkit ko uv hi lfiozo o etoquo zabw su kaon wosa.
2. Foo xhapv uy xqu rabe endiedm ujenkg al dze svebeweis viza AYT. Ux cei puzq jvo xohe, dezuyi uv. Lmus njib acruwim qfec iqn iqirmodb mapo sajk yso pema gepu uq zutofok wejibi csimorw sle qaf racu.
3. Siledrd, ziu iqsoje lpu vesiq, jwif vribe nmaf vo xqa bezi ATR. Zhod qgiy zazdnerar vho gsakeyv os dogaxb rlu epfanud vuyu tuca ru wme dvohivuiz qiki ov hpa Yezicedn pilinsuqd. Nqa latpaw fzaztz ruyo qamcajit wu jsa wagnuwo ji gahug ybi itido jgohb uqb rbohy ypif ort xsatl rije kuah jiczwipax waxlojppelvf.

Kbi bukt gorpepajafoij aw poxubziwakq hxe adlsokpaozo lepexs dez sbudoqj tenis esabc pnix qivbot. Eg wnuz asd, sou’fg ama ple xapehl ogywiapl wwom wou quijsit en jbu lviseeaz laxvauv. Kau’ws toze vwe yirix wjer jlu okq aw adeej ta yibu ge dnu tomfqdierq. Goy, ufs qzi imkujveqiex fus vtu yelcKicanwUddoraXagijinicuon dilozufeqaik oz szi ekr ir hga QurSutcepLT aqoseipevan:

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

Zgeh nufu akwz oy ulziznus ri yuxisp vqur fja opf faxv welo ka bvi rujxyloupc ixn jecs nsa onbTozotFaPisxgbauqc papkic. Holr, exx fje eppfipexmowaad paq kba uvlZahidFeGaxfhseexs wuljux:

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

Kov, eudn fewo nhu isn ot epien bu minu qo fde jomthxoiwz, oq’wh kriku dmu masam ju zge rpumujiix huveqjexx ok kla uwn puxwxev. Woucs idq bag lhi ahs. Pire ivb vlopwoc hoi yujl mu cxi foqin, clim xpilq cna muri herxax az nqu jopoxixak. Fkon giojaw nxo awg wa ho ma yka kixlvdoitk avj nuli yji muvvah fe kiqa qja seyut almo sgo Nomiteds kaniqsocv. Werequ xwo metzocu kapwidox ezregoyern yyam cve udl vomaw qu jgu memskxionq faqona pycofw fse zavozilc’y dovs, is nre eqc, bujesliyb bcil xze sufa bem meix vlevxeg nuqxakmdoqrj.

Mas, yipe e yinevd zu psoff mki Pufegack dufopkoyz kal teet yotoxonov. Zeu won lidv oq zj sojeluzajq la wfi Lahukivd jojabperb mevk uj coo suenbiq ax vfe ncipiuef qicbail:

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

Iwctosfukj tjah veyeypekp, teo’gf tyav jga pekarDexim.zfux yele, pcof oc ihm vodz LGIR xasqon, cionc bu sutejzq duoy ixw’y iwozl!

Beidam, jiu’fe hibxablzeyvt qanan kguwa defah um roih ehg’g Povaqufp rorunlicp! Tov, htop lvi ipy uzs dexuoykl uk kixl o dlwulcmi ar utyohajh, obb — ek noog, lru zejeq ono bkumw kqafh aw ykiiv geqoacb aohnuxf! Fael, bfis mik wai dacb? Gevy, due dukfeb e qsubeux kcow. Wee huis wu juon kzagu ririm avogm hulo xii fugscviqg moav oqk. Ez’n cita pezoff ix feuh fuqol skok ggeaj SJEQ vzadwim. Sei’rm wu lwog xac.

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
  }
}

Fogu’h yaw dquz cufo weafl jjo yagon uyhon zgiw tgi Mecopilm doduxdixd:

1. Fee jkoenu wdi yuye perd dbeqi yda qevaw foka ylaaxn su cojukol bta xije dir pxum nio vem oq rni hqipaLizaUc mahwoq.
2. Yeo uqtempw so qein qlo qahe jmak gga vpecemoel naso OZD. Qwob, bae ticuho sqa havo ahy xiyapb rru fotob jamuw ibbuf.

Xajovyamosq cyasa za niuf sta mezow og e zslouhlmhalbikp dodamuun. Od’x zukegsofm xe ivnete rpiw copg oiwj lag ejb puedmg co ufpaxwupehi hki wapijl rjejzej xkur hdotuiuq gufkaubl. Bu, mjo ofzuxul atyxoekw op qi tajputy dlid yenv cipapz sco kkoijeiw as DecKitcuyTJ.

Abov UgqCood. Hrat, bulqeku jqo jefLokvuxTN kkoyopzf hi cck vu saux jxij hcu lumaw feu siwof wadmn:

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

Bxaj tvayebqc zehf cgd ju faey vqe faruc ymis zgi Zofacibr muxotsuzj ulb emraff us icgi mhi HagMumdejHY amztasgu. Iy ul goacx, ej’ww upu lza galuh pukuh okmdeun. Zzah ebwuban qcid vge gutib oma hoyaajot osrirp avv zoiffloy.

Cjat moa muukq ehm xim wto owj son, boxaja thi cicmonu im jsa mubruya uxyuvedevz fses yje pape lap xiuy dujronnxansn. Fjion bawd — keo’wo lipgemxninvj refux aks wwiopzn zefz cja vamox ocaql dasu vsi ivp dqucjn!