Background Processing Reference

Complete API reference for iOS background execution. Covers all task types from BGTaskScheduler registration through SwiftUI integration, with code examples 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 on background transition
• Background URLSession for downloads that survive app termination
• Silent push notification handling
• SwiftUI .backgroundTask modifier patterns

Example Prompts

Questions you can ask Claude 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 -- ~30s runtime, scheduling with earliestBeginDate, continuous refresh pattern
• BGProcessingTask -- Multi-minute runtime, requiresExternalPower and requiresNetworkConnectivity constraints, progress checkpointing
• BGContinuedProcessingTask (iOS 26+) -- User-initiated work with system progress UI, dynamic registration, wildcard identifiers, GPU access
• beginBackgroundTask -- ~30s finalization window, proper endBackgroundTask cleanup
• Background URLSession -- Discretionary downloads, sessionSendsLaunchEvents, delegate lifecycle
• Silent push notifications -- Payload format, APNS priority, rate limiting behavior
• SwiftUI integration -- .backgroundTask(.appRefresh) and .backgroundTask(.urlSession) modifiers
• Testing -- LLDB simulate launch/expiration commands, console log filters, getPendingTaskRequests
• System constraints -- 7 scheduling factors, thermal state, Low Power Mode detection

Documentation Scope

This page documents the axiom-background-processing-ref reference skill -- comprehensive API coverage Claude uses when you need specific background task APIs, configuration details, or implementation patterns.

• For implementation guidance and decision trees, see background-processing
• For troubleshooting "task never runs" and other issues, see background-processing-diag

Related

• background-processing — Patterns, decision trees, and implementation guidance
• background-processing-diag — Symptom-based troubleshooting
• energy — Battery optimization for background work
• swift-concurrency — Async/await and task cancellation patterns

Resources

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

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