Scanning Options

ScanningOptions (ScanningOptions) controls IBluetoothScanner.StartScanningAsync(): permission behavior, advertisement filtering, scan mode/power trade-offs, and platform-specific parameters. See the type's generated page for the full property list — the source XML docs already include per-property platform-support notes.

Basic Usage

var options = new ScanningOptions
{
    ServiceUuids = [myServiceUuid],
    ScanMode = BluetoothScanMode.Balanced,
    IgnoreDuplicateAdvertisements = true
};

await scanner.StartScanningAsync(options);

Filtering

Three filtering mechanisms compose together:

  • ServiceUuids — hardware-level filter (fastest, most battery-efficient; applied by the OS radio itself where supported)
  • RssiThreshold — reject weak-signal advertisements before they reach your code
  • AdvertisementFilter — a Func<IBluetoothAdvertisement, bool> predicate for anything hardware/RSSI filtering can't express

IgnoreDuplicateAdvertisements + CallbackType (BluetoothScanCallbackType) together decide whether you get one callback per device (discovery) or one per advertisement packet (RSSI/presence tracking).

Android-Specific Options

AndroidScanningOptions — MatchMode/ScanMatchNumber (API 23+), ReportDelay (batches results instead of delivering them immediately), Phy and Legacy (API 26+).

Best Practices

  • Always specify ServiceUuids when you know what you're looking for — scanning for everything costs battery and CPU for no benefit.
  • Match ScanMode to the use case — LowLatency while a user is actively waiting on a device picker, LowPower for background monitoring (see Enumerations).
  • Enable duplicate filtering for pure discovery (IgnoreDuplicateAdvertisements = true, CallbackType = FirstMatch); disable it when tracking RSSI/presence over time.
  • Set ScanStartRetry = RetryOptions.Aggressive in production to absorb transient scan-start failures.
  • Use AndroidScanningOptions.ReportDelay to batch results and reduce wakeups when you don't need immediate delivery.
  • Layer filters: hardware ServiceUuids first, then RssiThreshold, then AdvertisementFilter for anything more complex.
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