Day 13 · 1부 · SwiftData로 저장하기

import Foundation
import SwiftData

enum Season: String, Codable, CaseIterable {
    case spring, summer, autumn, winter
}

@Model
final class Trip {
    @Attribute(.unique) var name: String      // 이름 중복 금지
    var destination: String
    var startDate: Date
    var season: Season                         // Codable enum → 그대로 저장
    @Relationship(deleteRule: .cascade, inverse: \Activity.trip)
    var activities: [Activity] = []           // 여행을 지우면 활동도 지운다
    @Transient var isHighlighted = false       // 저장하지 않는 값

    init(name: String, destination: String, startDate: Date, season: Season = .summer) {
        self.name = name
        self.destination = destination
        self.startDate = startDate
        self.season = season
    }
}

@Model
final class Activity {
    var name: String
    var isComplete = false
    var trip: Trip?

    init(name: String) {
        self.name = name
    }
}

import SwiftUI
import SwiftData

@main
struct TripsApp: App {
    var body: some Scene {
        WindowGroup {
            TripListView()
        }
        .modelContainer(for: [Trip.self, Activity.self])  // 환경에 modelContext가 들어간다
    }
}

import SwiftUI
import SwiftData

struct TripListView: View {
    @Environment(\.modelContext) private var context
    @Query(sort: \Trip.startDate, order: .reverse) private var trips: [Trip]

    var body: some View {
        NavigationStack {
            List {
                ForEach(trips) { trip in
                    NavigationLink(trip.name, destination: TripEditor(trip: trip))
                }
                .onDelete { offsets in
                    for index in offsets {
                        context.delete(trips[index])   // 삭제 표시 → 자동 저장
                    }
                }
            }
            .toolbar {
                Button("추가", systemImage: "plus") {
                    let trip = Trip(name: "여행 \(UUID().uuidString.prefix(4))",   // name은 .unique — 겹치면 새로 추가되지 않고 기존 행을 덮어쓴다(upsert)
                                    destination: "서울", startDate: .now)
                    context.insert(trip)               // 넣기만 하면 Query가 알아서 갱신
                }
            }
        }
    }
}

struct TripEditor: View {
    @Bindable var trip: Trip          // 복사본·편집용 모델 없이 원본에 직접

    var body: some View {
        Form {
            TextField("이름", text: $trip.name)
            TextField("목적지", text: $trip.destination)
            DatePicker("출발", selection: $trip.startDate, displayedComponents: .date)
        }
    }
}

struct UpcomingTripsView: View {
    @Query private var trips: [Trip]            // 전부 가져온다

    var body: some View {
        List(trips.filter { $0.startDate > .now }) { trip in   // body마다 다시 거른다
            Text(trip.name)
        }
    }
}

struct UpcomingTripsView: View {
    @Query private var trips: [Trip]

    init(after date: Date) {
        _trips = Query(filter: #Predicate<Trip> { $0.startDate > date },
                       sort: \.startDate)
    }

    var body: some View {
        List(trips) { trip in Text(trip.name) }
    }
}

struct RecentTripsView: View {
    static var recent: FetchDescriptor<Trip> {
        var descriptor = FetchDescriptor<Trip>(sortBy: [SortDescriptor(\.startDate, order: .reverse)])
        descriptor.fetchLimit = 5                   // 최근 5개만
        return descriptor
    }
    @Query(RecentTripsView.recent) private var trips: [Trip]

    var body: some View {
        List(trips) { trip in Text(trip.name) }
    }
}

struct StaleTripsView: View {
    @Environment(\.modelContext) private var context

    var body: some View {
        let trips = (try? context.fetch(FetchDescriptor<Trip>())) ?? []   // 관찰 없음
        List(trips) { Text($0.name) }
    }
}

struct LiveTripsView: View {
    @Query private var trips: [Trip]   // 저장소 변화 → 결과 갱신 → 뷰 다시 그림

    var body: some View {
        List(trips) { Text($0.name) }
    }
}