Background Processing Reference

API reference for running work while your iOS app is in the background, from BGTaskScheduler registration through SwiftUI integration. It's for developers who need exact APIs, Info.plist keys, and limits, with code examples drawn from WWDC sessions.

When to Use This Reference

Use this reference when you need:

• BGTaskScheduler registration and Info.plist configuration
• BGAppRefreshTask scheduling and handler patterns
• BGProcessingTask with power and network constraints
• BGContinuedProcessingTask (iOS 26+) for user-initiated work with progress UI
• beginBackgroundTask for finishing critical work as the app moves to the background
• A background URLSession for downloads that survive app termination
• Silent push notification handling
• SwiftUI .backgroundTask modifier patterns

Example Prompts

Questions you can ask your assistant that will draw from this reference:

• "How do I register a BGTaskScheduler handler correctly?"
• "What's the difference between BGAppRefreshTask and BGProcessingTask?"
• "How do I use BGContinuedProcessingTask in iOS 26 for photo export?"
• "How do I set up a background URLSession that continues after app termination?"
• "What's the correct AppDelegate handler for background URLSession events?"
• "How do I use the SwiftUI backgroundTask modifier?"
• "How do I handle silent push notifications for background refresh?"
• "What are the LLDB commands to test background tasks?"

What's Covered

• BGTaskScheduler registration – Info.plist configuration, handler registration timing, identifier matching
• BGAppRefreshTask – ~30-second runtime, scheduling with earliestBeginDate, BGTaskScheduler.Error cases, continuous refresh pattern
• Async submission (iOS and tvOS 27) – submitTaskRequest(_:), which replaces the deprecated synchronous submit(_:)
• BGProcessingTask – Multi-minute runtime, requiresExternalPower and requiresNetworkConnectivity, progress checkpointing, CPU Monitor disabled while on external power
• BGContinuedProcessingTask (iOS 26+, iOS only) – User-initiated work with system progress UI, dynamic registration, wildcard identifiers, .fail and .queue strategies, mandatory progress reporting, GPU access
• beginBackgroundTask – ~30-second finalization window, prompt endBackgroundTask cleanup
• Background URLSession – Discretionary downloads, sessionSendsLaunchEvents, the AppDelegate handler, delegate lifecycle
• Testing – LLDB commands that simulate launch and expiration, Console filters, getPendingTaskRequests
• System constraints – The 7 scheduling factors, Low Power Mode, Background App Refresh status, thermal state
• Silent push notifications – Payload format, APNs priority, rate limiting
• SwiftUI integration – .backgroundTask(.appRefresh) and .backgroundTask(.urlSession) modifiers, cancellation with Swift concurrency

Documentation Scope

This page documents the background-processing-ref skill (in the axiom-integration suite), the API reference your assistant uses for background task APIs, configuration details, and implementation patterns.

Related

• background-processing – Choosing the right task type, with decision trees and implementation guidance
• background-processing-diag – Troubleshooting tasks that never run or get terminated, by symptom
• energy – Keeping background work from draining the battery
• swift-concurrency – The async/await and task cancellation patterns the SwiftUI modifier relies on

Resources

WWDC: 2019-707, 2020-10063, 2022-10142, 2023-10170, 2025-227

Docs: /backgroundtasks, /backgroundtasks/bgtaskscheduler, /foundation/urlsessionconfiguration