import SwiftUI
struct PostsListView: View {
@StateObject private var viewModel = PostsListViewModel()
var body: some View {
NavigationView {
List {
ForEach(viewModel.posts) { post in
NavigationLink {
PostDetailView(postId: post.id)
} label: {
PostRowView(post: post)
.onAppear {
if post.id == viewModel.posts.last?.id {
viewModel.loadMoreIfNeeded()
}
}
}
}
if viewModel.isLoadingMore {
HStack {
Spacer()
ProgressView()
Spacer()
}
}
}
.listStyle(.plain)
.navigationTitle("Posts")
.refreshable {
await viewModel.refresh()
}
.overlay {
if viewModel.isLoading && viewModel.posts.isEmpty {
ProgressView()
} else if viewModel.posts.isEmpty {
ContentUnavailableView(
"No Posts",
systemImage: "doc.text",
description: Text("No posts available")
)
}
}
.alert("Error", isPresented: $viewModel.showError) {
Button("OK") { }
} message: {
Text(viewModel.errorMessage ?? "Unknown error")
}
}
.task {
await viewModel.loadInitialPosts()
}
}
}
struct PostRowView: View {
let post: Post
var body: some View {
VStack(alignment: .leading, spacing: 8) {
Text(post.title)
.font(.headline)
Text(post.body)
.font(.subheadline)
.foregroundColor(.secondary)
.lineLimit(2)
HStack {
Label("\(post.likesCount)", systemImage: "heart")
Label("\(post.commentsCount)", systemImage: "bubble.left")
Spacer()
Text(post.createdAt, style: .relative)
}
.font(.caption)
.foregroundColor(.secondary)
}
.padding(.vertical, 4)
}
}
import Foundation
import Combine
@MainActor
class PostsListViewModel: ObservableObject {
@Published var posts: [Post] = []
@Published var isLoading = false
@Published var isLoadingMore = false
@Published var errorMessage: String?
@Published var showError = false
private var currentPage = 1
private var hasMore = true
private let apiService = APIService.shared
func loadInitialPosts() async {
guard !isLoading else { return }
isLoading = true
errorMessage = nil
currentPage = 1
do {
let newPosts = try await apiService.fetchPosts(page: currentPage)
posts = newPosts
hasMore = newPosts.count >= 20 // Assuming 20 per page
} catch {
errorMessage = error.localizedDescription
showError = true
}
isLoading = false
}
func refresh() async {
await loadInitialPosts()
}
func loadMoreIfNeeded() {
guard !isLoadingMore && hasMore else { return }
Task {
isLoadingMore = true
currentPage += 1
do {
let newPosts = try await apiService.fetchPosts(page: currentPage)
posts.append(contentsOf: newPosts)
hasMore = newPosts.count >= 20
} catch {
errorMessage = error.localizedDescription
showError = true
currentPage -= 1 // Rollback on error
}
isLoadingMore = false
}
}
}
Lists are fundamental to iOS apps, displaying scrollable collections efficiently. SwiftUI's List or ScrollView with LazyVStack renders items on-demand. I add pull-to-refresh with the .refreshable modifier, calling async refresh logic. For infinite scroll, I detect when the last item appears using onAppear and trigger pagination. The ViewModel tracks current page and hasMore state. Pagination prevents duplicate loads with loading flags. For performance with large datasets, I use LazyVStack instead of VStack to avoid rendering off-screen views. This pattern provides smooth, responsive lists that scale to thousands of items.
