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SwiftUI-da Core Data va @FetchRequest bilan ishlash

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Bu videoda Core Data ko'rib chiqiladi. Bu — iPhone ichida saqlanadigan to'liq ma'lumotlar bazasi. Foydalanuvchi ilovani yopib qayta ochsa ham, ma'lumotlar o'chib ketmaydi.

Core Data vs UserDefaults

UserDefaults / AppStorageCore Data
MaqsadKichik ma'lumotlar (ism, sozlama)Katta hajmdagi ma'lumotlar bazasi
SaqlashKalit-qiymatJadval (entity) shaklida
Qidiruv va saralashYo'qNSSortDescriptor, NSPredicate
Qachon ishlatishOddiy sozlamalarRo'yxatlar, ilovaning asosiy ma'lumotlari

1-qadam: Yangi loyihada Core Data yoqish

Xcode-da yangi loyiha yaratishda: Use Core Data katagini belgilash. Apple avtomatik quyidagilarni yaratib beradi:

  • Persistence.swift — ma'lumotlar bazasini boshqaruvchi fayl
  • .xcdatamodeld — entity va atributlar sxemasi
  • Tayyor ContentView — oddiy misol

Arxitektura — asosiy komponentlar

PersistenceController — Singleton

struct PersistenceController {

    // Singleton — butun ilova bo'ylab bitta instance
    static let shared = PersistenceController()

    // Preview uchun alohida instance
    static var preview: PersistenceController = {
        let result = PersistenceController(inMemory: true)
        let viewContext = result.container.viewContext

        // Preview uchun soxta ma'lumotlar
        for x in 0..<10 {
            let newFruit = FruitEntity(context: viewContext)
            newFruit.name = "Apple \(x)"
        }
        try? viewContext.save()
        return result
    }()

    // NSPersistentContainer — ma'lumotlar bazasi o'zi
    let container: NSPersistentContainer

    init(inMemory: Bool = false) {
        // Nom = .xcdatamodeld fayl nomi bilan bir xil bo'lishi shart
        container = NSPersistentContainer(name: "CoreDataBootcamp")

        if inMemory {
            container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
        }

        container.loadPersistentStores { _, error in
            if let error = error {
                // Development vaqtida crash qilish — xato bor bo'lsa darhol bildirish
                // Production-da bu qatorni olib tashlash tavsiya etiladi
                fatalError("Xato: \(error.localizedDescription)")
            }
        }
    }
}

App.swift — viewContext-ni muhitga qo'yish

@main
struct CoreDataBootcampApp: App {

    let persistenceController = PersistenceController.shared

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environment(
                    \.managedObjectContext,
                    persistenceController.container.viewContext
                )
        }
    }
}

viewContext — ma'lumotlar bazasidagi aktiv ish maydoni. Barcha o'qish, yozish va o'chirish shu context orqali amalga oshiriladi.

2-qadam: FruitEntity yaratish

.xcdatamodeld faylida:

  1. Mavjud Item entity-ni o'chirish
  2. Add Entity → FruitEntity deb nomlash
  3. Add Attribute → name, turi String

Saqlash mumkin bo'lgan turlar: String, Int16/32/64, Double, Float, Bool, Date, UUID, Binary Data. Rasm yoki rang to'g'ridan-to'g'ri saqlanmaydi — Binary Data-ga konvertatsiya qilish kerak.

Xcode entity yaratilgandan so'ng, Xcode-ni qayta ishga tushirish tavsiya etiladi — ba'zan yangi entity avtomatik topilmaydi.

3-qadam: @FetchRequest — ma'lumotlarni olish

struct ContentView: View {

    // muhitdan viewContext olish
    @Environment(\.managedObjectContext) private var viewContext

    // FruitEntity-larni ma'lumotlar bazasidan olish
    @FetchRequest(
        entity: FruitEntity.entity(),
        sortDescriptors: [
            NSSortDescriptor(
                keyPath: \FruitEntity.name,
                ascending: true  // A → Z tartibda
            )
        ]
    ) var fruits: FetchedResults<FruitEntity>

    @State private var textFieldText: String = ""

    var body: some View {
        NavigationView {
            VStack(spacing: 20) {

                // Kiritish maydoni
                TextField("Meva nomini kiriting...", text: $textFieldText)
                    .font(.headline)
                    .padding(.leading)
                    .frame(height: 55)
                    .frame(maxWidth: .infinity)
                    .background(Color(.systemGray5))
                    .cornerRadius(10)
                    .padding(.horizontal)

                // Qo'shish tugmasi
                Button {
                    addItem()
                } label: {
                    Text("Qo'shish")
                        .font(.headline)
                        .foregroundColor(.white)
                        .frame(height: 55)
                        .frame(maxWidth: .infinity)
                        .background(Color.blue)
                        .cornerRadius(10)
                }
                .padding(.horizontal)

                // Mevalar ro'yxati
                List {
                    ForEach(fruits) { fruit in
                        Text(fruit.name ?? "")
                            .onTapGesture {
                                updateItem(fruit: fruit)
                            }
                    }
                    .onDelete(perform: deleteItems)
                }
                .listStyle(PlainListStyle())
            }
            .navigationTitle("Mevalar ro'yxati")
            .navigationBarItems(leading: EditButton())
        }
        .onAppear {
            // Ilova ochilganda ma'lumotlar @FetchRequest orqali avtomatik yuklanadi
        }
    }
}

CRUD funksiyalari

Create — qo'shish

private func addItem() {
    withAnimation {
        // Yangi entity yaratish
        let newFruit = FruitEntity(context: viewContext)
        newFruit.name = textFieldText  // textFieldText qiymatini saqlash

        // Saqlash va textField-ni tozalash
        saveItems()
        textFieldText = ""
    }
}

Read — o'qish

@FetchRequest bu ishni avtomatik bajaradi — fruits massivi doim yangilanib turadi. Qo'shimcha kod shart emas.

Update — yangilash

private func updateItem(fruit: FruitEntity) {
    withAnimation {
        // Entity-ni bevosita tahrirlash
        let currentName = fruit.name ?? ""
        let newName = currentName + "!"  // Misol: "Apple" → "Apple!"
        fruit.name = newName

        // Saqlash
        saveItems()
    }
}

Delete — o'chirish

private func deleteItems(offsets: IndexSet) {
    withAnimation {
        // IndexSet-dan birinchi indexni olish
        guard let index = offsets.first else { return }

        let fruitEntity = fruits[index]
        viewContext.delete(fruitEntity)

        saveItems()
    }
}

Save — saqlash (umumiy funksiya)

private func saveItems() {
    do {
        try viewContext.save()
    } catch {
        // Production-da bu yerda fatalError emas, xatoni log qilish tavsiya etiladi
        fatalError("Saqlash xatosi: \(error.localizedDescription)")
    }
}

NSSortDescriptor — tartiblash

// A → Z tartibda
NSSortDescriptor(keyPath: \FruitEntity.name, ascending: true)

// Z → A tartibda
NSSortDescriptor(keyPath: \FruitEntity.name, ascending: false)

// Bir nechta mezon bo'yicha
sortDescriptors: [
    NSSortDescriptor(keyPath: \FruitEntity.name, ascending: true),
]

@FetchRequest va MVVM

Bu videoda barcha logika View ichida yozildi — bu boshlang'ich uchun tushunish osonroq. Lekin professional ilovalarda bu yondashuv MVVM arxitekturasiga to'g'ri kelmaydi: View-da faqat UI bo'lishi kerak, ma'lumot logikasi esa ViewModel-da bo'lishi kerak.

Bu video:    View = UI + @FetchRequest + CRUD funksiyalari
MVVM usuli:  View = faqat UI
             ViewModel = @FetchRequest + CRUD funksiyalari

Keyingi videoda xuddi shu Core Data logikasi MVVM arxitekturasi bilan qayta yoziladi.

Xulosa

QadamNima qilinadi
Yangi loyiha"Use Core Data" belgilash
Persistence.swiftPersistenceController (Singleton) + container
App.swiftviewContext-ni muhitga qo'yish
.xcdatamodeldEntity va atributlar yaratish
View@Environment(\.managedObjectContext) + @FetchRequest
CRUDaddItem, deleteItems, updateItem, saveItems

Core Data — katta hajmdagi ma'lumotlarni qurilmada doimiy saqlash uchun kuchli va samarali vosita. Sessiyalar orasida saqlanishi, saralash va filtrlash imkoniyatlari uni real ilovalarda asosiy ma'lumot ombori sifatida ishlatishga imkon beradi.

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