Day 9 · 1부 · 리스트와 iOS 17 스크롤

import SwiftUI

struct Todo: Identifiable, Hashable {
    let id = UUID()
    var title: String
    var isDone = false
}

struct TodoListView: View {
    @State private var todos: [Todo] = [Todo(title: "우유"), Todo(title: "운동")]

    var body: some View {
        List {
            Section("오늘") {
                ForEach($todos) { $todo in
                    Text(todo.title)
                        .strikethrough(todo.isDone)
                        .swipeActions(edge: .leading) {
                            Button("완료") { todo.isDone.toggle() }
                                .tint(.green)
                        }
                        .swipeActions(edge: .trailing) {
                            Button("삭제", role: .destructive) {
                                todos.removeAll { $0.id == todo.id }
                            }
                        }
                }
            }
        }
        .refreshable {
            await reload()          // 끝날 때까지 스피너가 돈다
        }
        .overlay {
            if todos.isEmpty {
                ContentUnavailableView("할 일이 없다", systemImage: "checkmark.circle")
            }
        }
    }

    private func reload() async {
        try? await Task.sleep(for: .seconds(1))
    }
}

import SwiftUI

struct FeedView: View {
    let posts = (1...500).map { "게시물 \($0)" }

    var body: some View {
        ScrollView {
            LazyVStack(spacing: 12, pinnedViews: [.sectionHeaders]) {
                Section {
                    ForEach(posts, id: \.self) { post in
                        Text(post)
                            .frame(maxWidth: .infinity, minHeight: 80)
                            .background(.quaternary, in: .rect(cornerRadius: 12))
                    }
                } header: {
                    Text("최신").font(.headline)
                        .frame(maxWidth: .infinity, alignment: .leading)
                        .padding(8)
                        .background(.bar)
                }
            }
            .padding(.horizontal)
        }
    }
}

import SwiftUI

struct Chore: Identifiable {
    let id = UUID()
    var title: String
    var isPinned = false
}

struct ChoreEditor: View {
    @State private var chores = [Chore(title: "공지", isPinned: true),
                                 Chore(title: "빨래"), Chore(title: "청소")]
    @State private var selection = Set<Chore.ID>()

    var body: some View {
        NavigationStack {
            List(selection: $selection) {
                ForEach(chores) { chore in
                    Text(chore.title)
                        .deleteDisabled(chore.isPinned)   // canEditRowAt
                        .moveDisabled(chore.isPinned)     // canMoveRowAt
                }
                .onDelete { chores.remove(atOffsets: $0) }              // IndexSet
                .onMove { chores.move(fromOffsets: $0, toOffset: $1) }  // moveRowAt
            }
            .toolbar {
                EditButton()                      // 편집 ↔ 완료
                Button("선택 삭제") {
                    chores.removeAll { selection.contains($0.id) }
                    selection.removeAll()
                }
                .disabled(selection.isEmpty)
            }
        }
    }
}

import SwiftUI

struct Dog: Identifiable {
    let id = UUID()
    var name: String
    var likesFetch: Bool
}

struct DogRow: View {
    let dog: Dog
    var body: some View { Text(dog.name) }
}

struct BadDogList: View {
    let dogs: [Dog]

    var body: some View {
        List {
            ForEach(dogs) { dog in
                if dog.likesFetch {            // ① 요소당 1개 또는 0개
                    AnyView(DogRow(dog: dog))  // ② 개수를 전혀 알 수 없다
                }
            }
            ForEach(dogs.filter { $0.likesFetch }) { dog in   // ③ 갱신마다 전체 순회
                DogRow(dog: dog)
            }
        }
    }
}

import SwiftUI

struct Dog: Identifiable {
    let id = UUID()
    var name: String
    var likesFetch: Bool
}

@Observable final class Kennel {
    var dogs: [Dog] = [] {
        didSet { fetchLovers = dogs.filter(\.likesFetch) }   // 데이터가 바뀔 때만
    }
    private(set) var fetchLovers: [Dog] = []
}

struct GoodDogList: View {
    let kennel: Kennel

    var body: some View {
        List {
            ForEach(kennel.fetchLovers) { dog in
                HStack {                       // 행 안의 분기는 행 수에 영향 없음
                    Text(dog.name)
                    if dog.name.count > 5 {
                        Image(systemName: "star.fill")
                    }
                }
            }
        }
    }
}

import SwiftUI

struct Pet: Identifiable {
    let id = UUID()
    var name: String
}

struct ToyGroup: Identifiable {
    let id: String          // 장난감 이름
    var pets: [Pet]
}

struct SectionedPets: View {
    let groups: [ToyGroup]

    var body: some View {
        List {
            ForEach(groups) { group in
                Section(group.id) {
                    ForEach(group.pets) { pet in
                        Text(pet.name)
                    }
                }
            }
        }
    }
}

import SwiftUI

struct ClippedShelf: View {
    var body: some View {
        ScrollView(.horizontal) {
            LazyHStack {
                ForEach(0..<10, id: \.self) { i in
                    Color.orange.frame(width: 240, height: 140)
                }
            }
        }
        .padding(.horizontal, 20)   // 스크롤뷰 자체가 20pt씩 좁아진다
    }
}

import SwiftUI

struct PeekingShelf: View {
    var body: some View {
        ScrollView(.horizontal) {
            LazyHStack {
                ForEach(0..<10, id: \.self) { i in
                    Color.orange.frame(width: 240, height: 140)
                }
            }
        }
        .contentMargins(.horizontal, 20, for: .scrollContent)
    }
}

import SwiftUI

struct Palette: Identifiable, Hashable {
    let id: Int
    var color: Color { Color(hue: Double(id) / 10, saturation: 0.6, brightness: 0.9) }
}

struct GalleryView: View {
    private let palettes = (0..<10).map(Palette.init)
    @State private var currentID: Palette.ID?
    @Environment(\.horizontalSizeClass) private var sizeClass

    var body: some View {
        VStack(alignment: .leading) {
            Text("현재: \(currentID.map(String.init) ?? "-")")
                .padding(.horizontal)
            ScrollView(.horizontal) {
                LazyHStack(spacing: 12) {
                    ForEach(palettes) { palette in
                        RoundedRectangle(cornerRadius: 16)
                            .fill(palette.color)
                            .aspectRatio(3 / 2, contentMode: .fit)
                            .containerRelativeFrame(.horizontal,
                                                    count: sizeClass == .regular ? 2 : 1,
                                                    spacing: 12)
                            .scrollTransition { content, phase in
                                content
                                    .scaleEffect(phase.isIdentity ? 1 : 0.9)
                                    .opacity(phase.isIdentity ? 1 : 0.6)
                            }
                    }
                }
                .scrollTargetLayout()             // 스냅·위치 계산 대상 = 이 스택의 자식들
            }
            .contentMargins(.horizontal, 20, for: .scrollContent)
            .scrollTargetBehavior(.viewAligned)   // 손을 떼면 카드 모서리에 멈춤
            .scrollPosition(id: $currentID)       // 읽기: 스크롤하면 갱신 / 쓰기: 대입하면 이동
            .scrollIndicators(.hidden)

            Button("처음으로") {
                withAnimation { currentID = palettes.first?.id }
            }
            .padding(.horizontal)
        }
    }
}