Background Operations

Overview

Shiny BLE supports background operations through delegates. These fire when Bluetooth events occur even when your app is in the background.

IBleDelegate

The IBleDelegate interface receives adapter state and peripheral connection events in the background.

public class MyBleDelegate : BleDelegate
{
    readonly ILogger<MyBleDelegate> logger;

    public MyBleDelegate(ILogger<MyBleDelegate> logger)
    {
        this.logger = logger;
    }

    public override Task OnAdapterStateChanged(AccessState state)
    {
        this.logger.LogInformation("BLE Adapter State: {State}", state);
        return Task.CompletedTask;
    }

    public override Task OnPeripheralStateChanged(IPeripheral peripheral)
    {
        this.logger.LogInformation(
            "Peripheral {Name} ({Uuid}) - {Status}",
            peripheral.Name,
            peripheral.Uuid,
            peripheral.Status
        );
        return Task.CompletedTask;
    }
}

Note

BleDelegate is a convenience base class that provides virtual no-op implementations. You can implement IBleDelegate directly if preferred.

Registration

Register your delegate during startup:

services.AddBluetoothLE<MyBleDelegate>();

iOS system alerts for background connections

On iOS and Mac Catalyst, CoreBluetooth can put its own alert in front of the user — “Accessory would like to open App” — when a peripheral connects, disconnects or sends a notification while your app is not in the foreground. Apple intends these for apps that do not declare the bluetooth-central background mode and so have no other way to tell the user something happened.

Shiny asks for all three by default. If your app connects from the background on purpose — for example one kept running by background location updates, connecting when it detects something and disconnecting afterwards — the alert appears on every connect, and for a device that streams notifications, once per packet. Turn them off (5.8.1+):

services.AddBluetoothLE(new AppleBleConfiguration
{
    NotifyOnConnection = false,
    NotifyOnDisconnection = false,
    NotifyOnNotification = false
});

The options apply to every connect the app issues. They have no effect on other platforms.

When to Use Delegates vs Observables

Scenario	Use
Respond to events while app is backgrounded	Delegate
Monitor connection state while app is in foreground	WhenStatusChanged() observable
React to adapter on/off changes globally	Delegate
UI-bound connection monitoring	Observable