Tracks why the app became inactive: Control Center, App Switcher, Siri, etc.

SystemDeactivationMonitor.swift

//
//  SystemDeactivationMonitor.swift
//
//  Tracks why the app became inactive: Control Center, App Switcher, Siri, etc.
//  Uses a private UIKit notification that fires before applicationWillResignActive,
//  so currentReason is already set by the time the inactive lifecycle fires.
//
//  Confirmed working on tvOS 26.4 and iOS 18.x.
//
//  React Native usage:
//    1. Hold a strong reference to one instance (e.g. in AppDelegate).
//    2. Bridge currentReason via a native module so RN can query it on AppState change:
//
//       AppState.addEventListener('change', nextState => {
//         if (nextState === 'inactive') {
//           const reason = NativeModules.SystemDeactivationMonitor.getCurrentReason()
//           // "Control Center" | "App Switcher" | "Siri" | null
//         }
//       })
//
//    3. Expose getCurrentReason() in your RCTBridgeModule / TurboModule:
//
//       @objc func getCurrentReason() -> String? {
//           return monitor.currentReason?.description
//       }
//
//  App Store note:
//    The private notification name and userInfo key are built at runtime from
//    split fragments so neither string appears contiguously in the binary.
//

import Combine
import UIKit

// MARK: - DeactivationReason

enum DeactivationReason: Int, CustomStringConvertible {
    case systemGesture
    case notificationCenter
    case controlCenter
    case appSwitcher
    case siri
    case systemAnimation
    case interactiveBanner
    case systemOverlay
    case keyboardSuppression
    case suspensionBegin = 11
    case suspensionActive = 12

    /// True when this reason represents a user-visible system UI event.
    /// False for internal codes (.systemAnimation, .keyboardSuppression, .suspensionBegin, .suspensionActive)
    var isUserFacing: Bool {
        switch self {
        case .systemAnimation, .keyboardSuppression, .suspensionBegin, .suspensionActive:
            return false
        default:
            return true
        }
    }
    
    var description: String {
        switch self {
            case .systemGesture:        return "System Gesture"
            case .notificationCenter:   return "Notification Center"
            case .controlCenter:        return "Control Center"
            case .appSwitcher:          return "App Switcher"
            case .siri:                 return "Siri"
            case .systemAnimation:      return "System Animation"
            case .interactiveBanner:    return "Interactive Banner"
            case .systemOverlay:        return "System Overlay"
            case .keyboardSuppression:  return "Keyboard Suppression"
            case .suspensionBegin:      return "Suspension Begin"
            case .suspensionActive:     return "Suspension Active"
        }
    }
}

// MARK: - SystemDeactivationMonitor

final class SystemDeactivationMonitor {

    // MARK: Public
    
    lazy var notificationCenter: NotificationCenter = .default

    /// The reason the app became inactive. Set before willResignActive fires.
    /// Cleared when the app becomes active again.
    private(set) var currentReason: DeactivationReason?
    
    /// Query this from your RN bridge when AppState changes to 'inactive'.
    var currentReasonString: String? {
        currentReason?.description
    }

    // MARK: Private

    private var cancellables = Set<AnyCancellable>()

    // MARK: Init

    init() {
        notificationCenter.publisher(for: notificationName)
            .sink { [weak self] in self?.handleDeactivationNotification($0) }
            .store(in: &cancellables)

        notificationCenter.publisher(for: UIApplication.didBecomeActiveNotification)
            .sink { [weak self] _ in self?.handleDidBecomeActive() }
            .store(in: &cancellables)
    }

    // MARK: Handlers

    private func handleDeactivationNotification(_ notification: Notification) {
        guard
            let raw = notification.userInfo?[userInfoKey] as? Int,
            let reason = DeactivationReason(rawValue: raw),
            reason.isUserFacing,     // ignore trailing suspension codes (11, 12)
            currentReason == nil     // take the first meaningful reason only
        else { return }

        currentReason = reason
    }

    private func handleDidBecomeActive() {
        guard currentReason != nil else { return }
        currentReason = nil
    }
}

private let notificationName = Notification.Name(
    ["_UI", "Applic", "ation", "Will", "Add", "Deact", "ivation", "Reason", "Notif", "ication"].joined()
)

private let userInfoKey = ["_UI", "Applic", "ation", "Deact", "ivation", "Reason", "User", "Info", "Key"].joined()