I have an app that connects to a BLE device and registers its services. I can create a notification when my app is running on foreground or background, but is it possible to show a notification when a message is recieved from the BLE device while the app has been killed by the user?
Notification from BLE device even when the app is killed by the user
An app will not be able to perform any BLE functions if the app had previously been force-closed by the user. Force close is considered a drastic choice by the user to say that they do not want the app to run, often because it misbehaved in some unrecoverable manner.
This is also the case if the user switches off Bluetooth, even afterwards they switch it back on again.
Recovery from a killed condition is only possible if not the user, but the system has killed the app, for example, in order to free resources. In order to be restored from a system killed condition or app crash, you need to opt in to the Bluetooth State Restoration as described in Core Bluetooth State Preservation and Restoration More information on when your app will or will not be restored is described at TN3115: Bluetooth State Restoration App Relaunch Rules
Argun Tekant / DTS Engineer / Core Technologies