BLE Scanning

iOS BLE Background Scanning Stops After Few Minutes to Hours

Hi everyone,

I'm developing a Flutter app using flutter_blue_plus that needs continuous BLE scanning in both foreground and background. Foreground scanning works perfectly, but background scanning stops after a few minutes (sometimes 1-2 hours).

Current Implementation (iOS)

Foreground Mode:

• Scans for 10 seconds with all target service UUIDs
• Batches and submits results every 10 seconds
• Works reliably ✅

Background Mode:

• Rotates through service UUIDs in batches of 7
• Uses 1-minute batch intervals
• Maintains active location streaming (Geolocator.getPositionStream)
• Switches modes via AppLifecycleState observer

// Background scanning setup
await FlutterBluePlus.startScan(
  withServices: serviceUuids,  // Batch of 7 UUIDs
  continuousUpdates: true,
);

// Location streaming (attempt to keep app alive)
LocationSettings(
  accuracy: LocationAccuracy.bestForNavigation,
  distanceFilter: 0,
);

Lifecycle Management:

AppLifecycleState.paused -> Start background mode
AppLifecycleState.resumed -> Start foreground mode

Questions:

1. Is there a documented maximum duration for iOS background BLE scanning? My scanning stops inconsistently (few minutes to 2 hours).

2. Does iOS require specific Background Modes beyond location updates to maintain BLE scanning? I have location streaming active but scanning still stops.

3. Are there undocumented limitations when scanning with service UUIDs in background that might cause termination?

4. Should I be using CoreBluetooth's state preservation/restoration instead of continuous scanning?

Info.plist Configuration:

<key>UIBackgroundModes</key>
<array>
    <string>bluetooth-central</string>
    <string>location</string>
</array>

Additional Context:

• Total service UUIDs: ~20-50 (varies by company)
• Scanning in batches of 7 to work around potential limitations
• Android version works fine with foreground service
• Location permission: Always
• iOS 14+ target

Any insights on iOS BLE background limitations or best practices would be greatly appreciated.

Thanks!