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WWDC 2025 - iOS 26 Background APIs Explained: BGContinuedProcessingTask Changes Everything

Background flow

Understanding the Background Runtime Foundation

The App Lifecycle Flow

  • Foreground State: App interface is active, receives full system resources and CPU time
  • Background Transition: Process remains alive but enters suspended state by default
  • Suspension Protection: System preserves battery life, privacy, and resources for foreground apps
  • Resume Process: App returns to foreground through app switcher with system restoration

Core System Principles

  • Energy Conservation: Every operation (CPU, GPU, network, Neural Engine) has battery cost
  • Resource Management: System manages memory, CPU time, and network bandwidth prioritization
  • Opportunistic Execution: Background runtime is discretionary, not guaranteed
  • Coalesced Work: System batches background activities to minimize device wake cycles

The Five Pillars of Background Excellence

1. Efficient Resource Usage

  • Minimize CPU cycles and memory footprint
  • Defer non-critical tasks until device charging
  • Keep operations lightweight and purpose-driven
  • Monitor impact in Battery Settings for user transparency

2. Minimal System Impact

  • Avoid bloated workloads that compete with foreground experience
  • Prefer batch processing over continuous operations
  • Respect system throttling and suspension signals
  • Design discrete, targeted tasks rather than broad operations

3. Resilient Architecture

  • Save incremental progress frequently
  • Handle expiration signals promptly
  • Design atomic operations that can resume from interruption
  • Trust system scheduling for optimal resource allocation

4. Courteous Behavior

  • Honor user preferences (Low Power Mode, Background App Refresh, Low Data Mode)
  • Ensure value delivered proportional to resource consumption
  • Respond to user intent when app removed from switcher
  • Maintain transparency about background activities

5. Adaptive Design

  • Account for dynamic conditions (network, CPU load, thermal state, battery level)
  • Design tasks to pick up where they left off
  • Clearly advertise task requirements to system
  • Maintain flexibility for varying runtime opportunities

Background Task Categories and Implementation

App Refresh Tasks (BGAppRefreshTask)

Purpose: Silent content fetching based on usage patterns
Best For: Frequently used apps requiring fresh content on launch

Key Characteristics:

  • System aligns scheduling with app usage history
  • Higher scheduling probability for frequently used apps
  • Automatic suspension when task completion closure returns

SwiftUI Implementation Pattern:

WindowGroup {
    ContentView()
}
.backgroundTask(.appRefresh("bundleID.appRefresh")) {
    await performContentRefresh()
}
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Background Push Notifications

Purpose: Server-initiated content updates
Best For: Infrequent, irregular remote document updates

Key Characteristics:

  • Push-based rather than pull-based updates
  • Always considered discretionary by system
  • Low priority delivery with coalescing for efficiency
  • Respect user intent when app removed from switcher

Processing Tasks (BGProcessingTask)

Purpose: Complex background operations (ML models, database maintenance)
Best For: Resource-intensive tasks that can be deferred

Key Features:

  • Support for network and power requirements
  • Immediate registration required during app launch
  • Configurable execution constraints for battery optimization

Implementation Pattern:

BGTaskScheduler.shared.register(
    forTaskWithIdentifier: "bundleID.processing",
    using: nil
) { task in
    handleProcessingTask(task as! BGProcessingTask)
}

// Configure requirements
let request = BGProcessingTaskRequest(identifier: "bundleID.processing")
request.requiresNetworkConnectivity = true
request.requiresExternalPower = true
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Begin/End Background Tasks

Purpose: Complete in-flight work during background transition
Best For: Critical operations that cannot be interrupted (state saves, file cleanup)

Implementation Strategy:

var backgroundTaskID: UIBackgroundTaskIdentifier = .invalid

func handleCriticalWork() {
    backgroundTaskID = UIApplication.shared.beginBackgroundTask(withName: "Critical Task") {
        // Expiration handler
        UIApplication.shared.endBackgroundTask(self.backgroundTaskID)
        self.backgroundTaskID = .invalid
    }

    performCriticalWork()

    UIApplication.shared.endBackgroundTask(backgroundTaskID)
    backgroundTaskID = .invalid
}
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iOS 26: Continued Processing Tasks

Revolutionary User-Initiated Background Processing

Purpose: Long-running tasks with system UI progress indication
Best For: Exports, uploads, complex processing initiated by explicit user action

Core Requirements

  • Explicit User Initiation: Must start with button tap or gesture, never automatic
  • Clear Goal Definition: Represents immediate, understandable objective
  • Measurable Progress: System requires continuous progress reporting
  • User Control: Users can monitor progress and cancel at any time

Implementation Architecture

1. Info.plist Configuration:

BGTaskSchedulerPermittedIdentifiers:
- com.yourapp.bundleid.userTask
- com.yourapp.bundleid.export.*  // Wildcard support
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2. Dynamic Handler Registration:

func prepareForUserTask() {
    BGTaskScheduler.shared.register("com.yourapp.userTask") { task in
        let continuedTask = task as! BGContinuedProcessingTask

        var shouldContinue = true
        task.expirationHandler = {
            shouldContinue = false
        }

        // Progress reporting is mandatory
        task.progress.totalUnitCount = 100
        task.progress.completedUnitCount = 0

        while shouldContinue && hasWork {
            performWorkUnit()
            task.progress.completedUnitCount += 1
        }

        task.setTaskCompleted(success: shouldContinue)
    }
}
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3. Task Submission with Strategy:

func submitUserInitiatedTask() {
    let request = BGContinuedProcessingTaskRequest(
        identifier: "com.yourapp.userTask",
        title: "Exporting Photos",
        subtitle: "Processing 147 items"
    )

    // Choose submission strategy
    request.strategy = .fail  // Fail if cannot start immediately
    // or .queue (default) for queued execution

    try? BGTaskScheduler.shared.submit(request)
}
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Advanced Capabilities

Background GPU Access (iOS 26):

  • Add background GPU capability in Xcode project settings
  • Query BGTaskScheduler.shared.supportedResources at runtime
  • System enforces resource requirements and rejects invalid requests
  • Dynamic adaptation based on device capabilities

Quality of Service Management:

  • Background tasks receive lower QoS compared to foreground
  • System intelligently boosts priority when app returns to foreground
  • Ensures smooth transition and responsive user experience

Development Best Practices

Pre-Development Questions

  1. Initiation Source: User-initiated vs. system-discretionary?
  2. Duration Classification: Short, medium, or long-running task?
  3. Criticality Assessment: Essential for app state vs. enhancement feature?
  4. User Interaction: Requires consent or input vs. autonomous operation?

Task Design Principles

  • Atomic Operations: Each task performs single, well-defined function
  • Resource Awareness: Understand and respect system constraints
  • Progress Transparency: Provide meaningful progress updates for user-facing tasks
  • Graceful Degradation: Handle interruption and resource limitations elegantly

System Integration

  • Registration Timing: Register background tasks immediately during launch
  • Handler Management: Use appropriate queues and threading for task execution
  • Error Handling: Implement robust error handling and recovery mechanisms
  • Resource Querying: Check device capabilities before requesting specialized resources

The evolution of iOS background runtime represents a sophisticated balance between user experience, system performance, and battery life.

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iOS 26 BGContinuedProcessingTask adds new limits

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