startBackgroundScan

Starts a background BLE scan that delivers results via a android.app.PendingIntent.

Unlike scanDevices, this method allows BLE scanning to continue even when your app is not in the foreground. Scan results are delivered to a android.content.BroadcastReceiver specified by the pendingIntent, enabling your app to react to nearby BLE devices without maintaining an active Activity or Service.

Setup Requirements

To use background scanning, you must:

1. Create a BroadcastReceiver to handle incoming scan results:

    class BleScanReceiver : BroadcastReceiver() {
        override fun onReceive(context: Context, intent: Intent) {
            val results = intent.getParcelableArrayListExtra<ScanResult>(
                BluetoothLeScanner.EXTRA_LIST_SCAN_RESULT
            )
            results?.forEach { result ->
                // Process discovered device
            }
        }
    }

   Content copied to clipboard

2. Register the receiver in your AndroidManifest.xml:

    <receiver android:name=".BleScanReceiver"
              android:exported="false" />

   Content copied to clipboard

3. Create a PendingIntent targeting your receiver:

    val intent = Intent(context, BleScanReceiver::class.java)
    val pendingIntent = PendingIntent.getBroadcast(
        context, REQUEST_CODE, intent,
        PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_MUTABLE
    )

   Content copied to clipboard

Battery Considerations

Background scanning can significantly impact battery life. Consider using:

• ScanSettings.SCAN_MODE_LOW_POWER or ScanSettings.SCAN_MODE_OPPORTUNISTIC

• Specific ScanFilter entries to reduce wake-ups

• Appropriate scan intervals based on your use case

Platform Limitations

• On Android 8.0+, background scans without filters may be throttled or ignored

• Some devices may limit the number of concurrent background scans

• Results may be batched and delivered with delays to conserve battery

Parameters

See also