Central.m

- (void)centralManager:(CBCentralManager *)central
  didConnectPeripheral:(CBPeripheral *)peripheral {
    [self.centralManager stopScan];

    peripheral.delegate = self;
    [peripheral discoverServices:@[[CBUUID UUIDWithString:kServiceUUID]]];
}

- (void)centralManager:(CBCentralManager *)central
didFailToConnectPeripheral:(CBPeripheral *)peripheral
                 error:(NSError *)error {
    [self cleanup:peripheral];
}

- (void)cleanup:(CBPeripheral *)cbPeripheral {
    [self.centralManager cancelPeripheralConnection:cbPeripheral];
}