Question

I am developing a proximity sensing application using bluetooth technology 4.0. I am able to discover the devices. But I am not able to pair with them. Nor can i call [peripheral readRssi] method. The way I want to achieve this is that if the central scans for say 10 devices and after finding those many, it should stop the scan and then pair the devices and then constantly read the RSSI values.

My piece of code.

- (void) centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI
{
    BOOL (^test)(id obj, NSUInteger idx, BOOL *stop);
    test = ^ (id obj, NSUInteger idx, BOOL *stop) {
        if([[[obj peripheral] name] compare:peripheral.name] == NSOrderedSame)
            return YES;
        return NO;
    };

    PeripheralCell* cell;
    NSUInteger t=[peripherals indexOfObjectPassingTest:test];
    if(t!= NSNotFound)
    {
        cell=[peripherals objectAtIndex:t];
        cell.peripheral=peripheral;
        cell.rssi=RSSI;
        //NSLog(@"%@",RSSI);
        [scanResultTableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:[NSIndexPath indexPathForRow:t inSection:0]] withRowAnimation:UITableViewRowAnimationNone];
    }
    else{
        cell=[[PeripheralCell alloc] init];
        [peripherals addObject: cell];
        [myPeripheral addObject: peripheral];
        cell.peripheral=peripheral;
        cell.rssi=RSSI;
        NSLog(@"UUID===%@",[peripheral UUID]);
        [scanResultTableView insertRowsAtIndexPaths:[NSArray arrayWithObject:[NSIndexPath indexPathForRow:[peripherals count]-1 inSection:0]] withRowAnimation:UITableViewRowAnimationNone];
        if([myPeripheral count]==3)
        {
            [manager stopScan];
            for(CBPeripheral *p in myPeripheral)
            {
                [manager connectPeripheral:p options:nil];      //this calls didConnectPeripheral but gets disconnected after some time 
                [p readRssi];     //this does not work even after connecting
            }
        }
    }
}

- (void)centralManagerDidUpdateState:(CBCentralManager *)central
{
    //self.cBReady = false;
    switch (central.state) {
        case CBCentralManagerStatePoweredOff:
            NSLog(@"CoreBluetooth BLE hardware is powered off");
            break;
        case CBCentralManagerStatePoweredOn:
            NSLog(@"CoreBluetooth BLE hardware is powered on and ready");
            //self.cBReady = true;
            break;
        case CBCentralManagerStateResetting:
            NSLog(@"CoreBluetooth BLE hardware is resetting");
            break;
        case CBCentralManagerStateUnauthorized:
            NSLog(@"CoreBluetooth BLE state is unauthorized");
            break;
        case CBCentralManagerStateUnknown:
            NSLog(@"CoreBluetooth BLE state is unknown");
            break;
        case CBCentralManagerStateUnsupported:
            NSLog(@"CoreBluetooth BLE hardware is unsupported on this platform");
            break;
        default:
            break;
    }
}

- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
    NSLog(@"connected peripheral");
}

- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;
{
    NSLog(@"peripheral disconnected");
}

- (void)peripheralDidUpdateRSSI:(CBPeripheral *)peripheral error:(NSError *)error
{
    NSLog(@"updated rssi");
}

how can i pair the devices…

Answer 1

After much searching and trail and error I found out that my code is correct. I just had to remove the devices from the ipad’s Setting.

Goto Settings > General > Bluetooth > Devices.

Select the device by clicking the accessory indicator. In the next screen just click on “Forget this Device”.

Running the application again solved my problem.