Enable Background Bluetooth Mode

[nionata]

By default the bluetooth scanning will only be done when the app is active. Read more here.

[nionata]

https://medium.com/@cbartel/ios-scan-and-connect-to-a-ble-peripheral-in-the-background-731f960d520d

[nionata]

I enabled both background mode for ble central and peripheral. Still requires a code change in the central for background scanning:

Pass restoreStateIdentifier and restoreStateFunction to BleManager constructor.