iOS: didDiscoverPeripheral not called in Background mode

Question

I am Working on BLE project, everything works fine when the app in the foreground.It can discover and connect to the peripheral, all the call back method work perfectly.

Answer 1

From Official Apple reference

You can provide an array of CBUUID objects—representing service UUIDs—in the serviceUUIDs parameter. When you do, the central manager returns only peripherals that advertise the services you specify (recommended). If the serviceUUIDs parameter is nil, all discovered peripherals are returned regardless of their supported services (not recommended). If the central manager is already scanning with different parameters, the provided parameters replace them. When the central manager object discovers a peripheral, it calls the centralManager:didDiscoverPeripheral:advertisementData:RSSI: method of its delegate object.

Apps that have specified the bluetooth-central background mode are allowed to scan while in the background. That said, they must explicitly scan for one or more services by specifying them in the serviceUUIDs parameter. The CBCentralManagerOptionShowPowerAlertKey scan option is ignored while scanning in the background.

Here

Apps that have specified the bluetooth-central background mode are allowed to scan while in the background. That said, they must explicitly scan for one or more services by specifying them in the serviceUUIDs parameter.

So scanForPeripheralsWithServices:nil with nil it will not work in background , you need to specify list of UUIDS