How to Build a Live Activity in SwiftUI

// MARK: - Shared: OrderAttributes.swift
// (Add this file to both your App target and Widget Extension target)

import ActivityKit
import Foundation

struct OrderAttributes: ActivityAttributes {
    /// Dynamic — changes during the activity's lifetime
    struct ContentState: Codable, Hashable {
        var status: String
        var eta: Date
        var courierName: String
    }
    /// Static — set once at launch
    let orderID: String
    let restaurantName: String
}

// ─────────────────────────────────────────────────────────────────
// MARK: - Widget Extension: OrderLiveActivityWidget.swift
// ─────────────────────────────────────────────────────────────────

import SwiftUI
import WidgetKit
import ActivityKit

struct OrderLiveActivityWidget: Widget {
    var body: some WidgetConfiguration {
        ActivityConfiguration(for: OrderAttributes.self) { context in
            // Lock Screen / StandBy view
            OrderLockScreenView(context: context)
                .activityBackgroundTint(Color.orange.opacity(0.15))
                .activitySystemActionForegroundColor(.orange)
        } dynamicIsland: { context in
            DynamicIsland {
                // Expanded (long-press)
                DynamicIslandExpandedRegion(.leading) {
                    Label("Order", systemImage: "bag.fill")
                        .font(.caption2)
                        .foregroundStyle(.orange)
                }
                DynamicIslandExpandedRegion(.trailing) {
                    Text(context.state.eta, style: .timer)
                        .font(.caption2.monospacedDigit())
                        .foregroundStyle(.secondary)
                }
                DynamicIslandExpandedRegion(.bottom) {
                    HStack {
                        Image(systemName: "bicycle")
                        Text(context.state.status)
                            .font(.subheadline.bold())
                        Spacer()
                        Text("ETA \(context.state.eta.formatted(.dateTime.hour().minute()))")
                            .font(.caption)
                            .foregroundStyle(.secondary)
                    }
                }
            } compactLeading: {
                Image(systemName: "bag.fill")
                    .foregroundStyle(.orange)
            } compactTrailing: {
                Text(context.state.eta, style: .timer)
                    .monospacedDigit()
                    .font(.caption2)
            } minimal: {
                Image(systemName: "bag.fill")
                    .foregroundStyle(.orange)
            }
            .widgetURL(URL(string: "myapp://order/\(context.attributes.orderID)"))
            .keylineTint(.orange)
        }
    }
}

struct OrderLockScreenView: View {
    let context: ActivityViewContext<OrderAttributes>

    var body: some View {
        HStack(spacing: 16) {
            Image(systemName: "bicycle.circle.fill")
                .font(.system(size: 44))
                .foregroundStyle(.orange)
                .accessibilityHidden(true)

            VStack(alignment: .leading, spacing: 4) {
                Text(context.state.status)
                    .font(.headline)
                Text("via \(context.attributes.restaurantName)")
                    .font(.subheadline)
                    .foregroundStyle(.secondary)
                Label(
                    "ETA \(context.state.eta.formatted(.dateTime.hour().minute()))",
                    systemImage: "clock"
                )
                .font(.caption)
                .foregroundStyle(.secondary)
            }
            Spacer()
        }
        .padding()
        .accessibilityElement(children: .combine)
        .accessibilityLabel(
            "\(context.state.status). ETA \(context.state.eta.formatted(.dateTime.hour().minute()))"
        )
    }
}

// ─────────────────────────────────────────────────────────────────
// MARK: - App side: LiveActivityManager.swift
// ─────────────────────────────────────────────────────────────────

import ActivityKit
import Foundation

@MainActor
final class LiveActivityManager: ObservableObject {
    private var activity: Activity<OrderAttributes>?

    func start(orderID: String, restaurant: String) {
        guard ActivityAuthorizationInfo().areActivitiesEnabled else { return }

        let attrs = OrderAttributes(orderID: orderID, restaurantName: restaurant)
        let state = OrderAttributes.ContentState(
            status: "Preparing your order",
            eta: .now.addingTimeInterval(1800),
            courierName: "Alex"
        )
        let content = ActivityContent(state: state, staleDate: .now.addingTimeInterval(3600))

        do {
            activity = try Activity.request(attributes: attrs, content: content)
        } catch {
            print("Live Activity failed: \(error)")
        }
    }

    func update(status: String, eta: Date) async {
        let newState = OrderAttributes.ContentState(
            status: status, eta: eta, courierName: "Alex"
        )
        let content = ActivityContent(state: newState, staleDate: nil)
        await activity?.update(content)
    }

    func end(finalStatus: String) async {
        let state = OrderAttributes.ContentState(
            status: finalStatus,
            eta: .now,
            courierName: "Alex"
        )
        let content = ActivityContent(state: state, staleDate: nil)
        await activity?.end(content, dismissalPolicy: .after(.now.addingTimeInterval(30)))
    }
}

// ─────────────────────────────────────────────────────────────────
// MARK: - Example view wiring
// ─────────────────────────────────────────────────────────────────

import SwiftUI

struct OrderTrackingView: View {
    @StateObject private var liveActivity = LiveActivityManager()

    var body: some View {
        VStack(spacing: 20) {
            Button("Start Live Activity") {
                liveActivity.start(orderID: "ORD-42", restaurant: "Sakura Ramen")
            }
            Button("Update: Out for delivery") {
                Task { await liveActivity.update(
                    status: "Out for delivery",
                    eta: .now.addingTimeInterval(600)
                )}
            }
            Button("End: Delivered!") {
                Task { await liveActivity.end(finalStatus: "Delivered!") }
            }
        }
        .buttonStyle(.borderedProminent)
    }
}

#Preview {
    OrderTrackingView()
}