Add getUuids() about flutter_blue

[peekpt]

@deakjahn
Bluetooth doesn't let you read device UUIDS before connecting. You have to put your uuids ( or whatever you want) on advertisement packet of your device and when scanning you have the option to filter for whatever uuids you advertise.

Please close

[deakjahn]

I have a PR that does much more, adds BluetoothClass and I added it there. If the platform supports it, shouldn't the plugin provide it? But I'm still experimenting with it in my code to see...

[deakjahn]

I did some experimenting and I definitely suggest to include it (either with the PR I provided or another). Yes, the system might not return it about foreign devices, without connection. But, as I found out, it most definitely returns both the UUIDs and the class items I included in the PR when you ask for paired (bonded) devices. So, there's a clear use case for them. You might want to mention this in the function docs block that it's only useful with already known and paired devices.