Getting list of bluetoooth devices ios

Question

I am developing a module in which I need to get all bleutooth devices and connect the selected device. I am using this

blueManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];

- (void)centralManagerDidUpdateState:(CBCentralManager *)central

{

  NSString *messtoshow;

    switch (central.state) {

    case CBCentralManagerStateUnknown:
    {
        messtoshow=[NSString stringWithFormat:@"State unknown, update imminent."];
        break;
    }
    case CBCentralManagerStateResetting:
    {
        messtoshow=[NSString stringWithFormat:@"The connection with the system service was momentarily lost, update imminent."];
        break;
    }
    case CBCentralManagerStateUnsupported:
    {
        messtoshow=[NSString stringWithFormat:@"The platform doesn't support Bluetooth Low Energy"];
        break;
    }
    case CBCentralManagerStateUnauthorized:
    {
        messtoshow=[NSString stringWithFormat:@"The app is not authorized to use Bluetooth Low Energy"];
        break;
    }
    case CBCentralManagerStatePoweredOff:
    {
        messtoshow=[NSString stringWithFormat:@"Bluetooth is currently powered off."];
        break;
    }
    case CBCentralManagerStatePoweredOn:
    {
        messtoshow=[NSString stringWithFormat:@"Bluetooth is currently powered on and available to use."];
          [self.blueManager scanForPeripheralsWithServices:nil options:nil];
          CBUUID *deviceInfoUUID = [CBUUID UUIDWithString:@"180A"];
        NSLog(@"connected devices ios 8 code%@  ",[blueManager retrieveConnectedPeripheralsWithServices:@[deviceInfoUUID]]);

}

and my bluetooth is on and connected to two devices which I can see from setting but I am not getting any device. I have checked in

- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI {}

method but it is not calling. And I know that two BLE devices is already connected to my device