not getting data / services from BLE device in ios - ios

Question

I need to connect with a BLE device and then handle data as per sent via different button in it.
For that I wrote following code.
import CoreBluetooth
class HomeViewController: UIViewController,CBPeripheralDelegate,CBCentralManagerDelegate
{
var centralManager : CBCentralManager!
var peri : CBPeripheral!
override func viewDidLoad()
{
super.viewDidLoad()
centralManager = CBCentralManager(delegate: self, queue: nil)
}
func centralManagerDidUpdateState(central: CBCentralManager) {
if central.state == .Unknown
{
print("Unknown")
}
else if central.state == .Unsupported
{
print("Unsupported")
}
else if central.state == .Unauthorized
{
print("Unauthorized")
}
else if central.state == .Resetting
{
print("Resetting")
}
else if central.state == .PoweredOn
{
print("Powered On")
startScan()
}
else if central.state == .PoweredOff
{
print("Powered Off")
}
}
func centralManager(central: CBCentralManager, didDiscoverPeripheral peripheral: CBPeripheral, advertisementData: [String : AnyObject], RSSI: NSNumber) {
print("Discovered: \(peripheral.name) at \(RSSI)")
print("AdvertisementData:\(advertisementData)")
if peri != peripheral
{
peri = peripheral
centralManager.connectPeripheral(peripheral, options: nil)
}
}
func centralManager(central: CBCentralManager, didFailToConnectPeripheral peripheral: CBPeripheral, error: NSError?) {
print("Failed to connect \(peripheral) cause of \(error)")
}
func centralManager(central: CBCentralManager, didConnectPeripheral peripheral: CBPeripheral) {
print("connected to \(peripheral)")
// centralManager.stopScan()
print("Available services:\(peripheral.services)")
}
func peripheral(peripheral: CBPeripheral, didDiscoverIncludedServicesForService service: CBService, error: NSError?) {
print("Services\(service) and error\(error)")
}
func peripheral(peripheral: CBPeripheral, didDiscoverServices error: NSError?) {
print("Services and error\(error)")
}
func startScan(){
print("Scanning...")
centralManager.scanForPeripheralsWithServices(nil, options: nil)
}
}
And here is my Log for this code.
Powered On
Scanning...
Discovered: Optional("**** BLE") at 127
AdvertisementData:["kCBAdvDataIsConnectable": 1, "kCBAdvDataServiceUUIDs": (
1802
)]
connected to <CBPeripheral: 0x12756d910, identifier = 6197****-EB0A-F1E8-BEF4-1AFAC629C5BC, name = **** BLE, state = connected>
Available services:nil
This is output is generated when one button is clicked from BLE device. But I am unable to receive or read data when another button is clicked.
Android developer of same app has integrated with both button.
So there is no any problem in device.
Can anyone help me to guide where I'm going wrong in this code??

Answer 1

Pandafox's answer is perfect just one thing is missing from it.
Which is setting delegate of peripheral.
Here is the complete code to discover peripheral, connect to it and discover its services and characteristics.
1.Connect peripheral
func centralManager(central: CBCentralManager, didDiscoverPeripheral peripheral: CBPeripheral, advertisementData: [String : AnyObject], RSSI: NSNumber) {
print("Discovered: \(peripheral.name) at \(RSSI)")
print("AdvertisementData:\(advertisementData)")
if peri != peripheral
{
peri = peripheral
peri.delegate = self
centralManager.connectPeripheral(peri, options: nil)
}
}
Connection failure or success
func centralManager(central: CBCentralManager, didFailToConnectPeripheral peripheral: CBPeripheral, error: NSError?) {
print("Failed to connect \(peripheral) cause of \(error)")
}
func centralManager(central: CBCentralManager, didConnectPeripheral peripheral: CBPeripheral) {
print("connected to \(peripheral)")
// centralManager.stopScan()
peripheral.discoverServices(nil)
}
3.DiscoverServices
func peripheral(peripheral: CBPeripheral, didDiscoverServices error: NSError?) {
print("Services:\(peripheral.services) and error\(error)")
if let services = peripheral.services {
for service in services {
peripheral.discoverCharacteristics(nil, forService: service)
}
}
}
Discover Characteristics and set notification
func peripheral(peripheral: CBPeripheral, didDiscoverCharacteristicsForService service: CBService, error: NSError?)
{
print("peripheral:\(peripheral) and service:\(service)")
for characteristic in service.characteristics!
{
peripheral.setNotifyValue(true, forCharacteristic: characteristic)
}
}
Handle notification for update value of characteristics
func peripheral(peripheral: CBPeripheral, didUpdateValueForCharacteristic characteristic: CBCharacteristic, error: NSError?)
{
print("characteristic changed:\(characteristic)")
}

Answer 2

You also have to discover the services and characteristics after connecting to the device.
For example, in your "didConnectPeripheral" method, you will have to do something like:
func centralManager(central: CBCentralManager, didConnectPeripheral peripheral: CBPeripheral) {
print("connected to \(peripheral)")
peripheral.delegate = self
peripheral.discoverServices(nil)
print("Discovering services!")
}
And then:
func peripheral(peripheral: CBPeripheral, didDiscoverServices error: NSError?) {
print("Discovered services: \(peripheral.services), Error\(error)")
if let services = peripheral.services {
for service in services {
peripheral.discoverCharacteristics(nil, forService: service)
}
}
}
And then you have to handle each characteristic:
func peripheral(peripheral: CBPeripheral, didDiscoverCharacteristicsForService service: CBService, error: NSError)
You must remember to store each characteristic manually, as they will be deallocated if you don't.
In order to receive streaming data (notifications) you will have to enable notify for each characteristic.
peripheral.setNotifyValue(true, forCharacteristic: characteristic)
You also have to implement:
func peripheral(peripheral: CBPeripheral, didUpdateValueForCharacteristic characteristic: CBCharacteristic, error: NSError)
Order to handle the incoming values.
As you can see, there's quite a bit of boiler plate code required to get started.

Answer 3

After connecting to the peripheral you have to call discoverServices on the peripheral with the UUID of the services you want to discover, you then have to discover the characteristics of the service. If you want updates when a button is clicked, you will have to turn notifications on for the characteristic corresponding to that button
I would highly recommend this link from apple for follow up reading if you still need help. It describes what you need to do step by step in a better fashion than I could ever describe here.
Apple BLE Guide