scanDevices

Scans for nearby BLE devices and emits discovered devices through a reactive Flow.

This method creates a cold Flow that starts BLE scanning when collected and automatically stops scanning when the collection is cancelled. The Flow is built using callbackFlow, which bridges the callback-based Android BLE API to Kotlin's coroutine-based Flow.

Flow Behavior

• Cold Flow: Scanning only begins when the Flow is actively collected. Multiple collectors will start separate scan sessions.

• Automatic Cleanup: When the collector's coroutine is cancelled (e.g., when a ViewModel is cleared or a lifecycle scope ends), the scan is automatically stopped via awaitClose.

• Error Handling: Scan failures are propagated as exceptions that can be caught using the Flow's catch operator.

Scan Modes

The scanSettings parameter controls how aggressively the scanner searches for devices:

• ScanSettings.SCAN_MODE_LOW_POWER: Minimal battery impact, slower discovery

• ScanSettings.SCAN_MODE_BALANCED: Balanced between power and latency

• ScanSettings.SCAN_MODE_LOW_LATENCY: Fastest discovery, highest battery usage (default)

Thread Safety

This method is safe to call from any coroutine context. The Flow will emit results on the dispatcher of the collecting coroutine.

Error Conditions

The Flow will close with an exception in the following cases:

• Bluetooth is disabled on the device

• BluetoothLeScanner is unavailable (null)

• The underlying scan fails (error code provided in exception message)

Parameters

See also

Throws