I've been writing an app using Swift that connects to a bluetooth BLE device. For some reason, the app doesn't always connect to the device. In this case it will connect but gets disconnected straight away. This only happens maybe 1 in 10 times it connects, but definitely interferes with the reliability of the app.
I'm using CoreBluetooth to connect to the BLE device. Attempting connection again usually always gets it to reconnect, and other apps that communicate with this device works correctly every time, so I'm confident that it is not a problem with the peripheral.
I'd just like to know if there is anyone out there who has had a similar issue or if there is a particular reason why this may be happening?
EDIT: Here's the code for the willSelectRow of my table. This is where I get the peripheral to connect.
func tableView(tableView: UITableView, willSelectRowAtIndexPath indexPath: NSIndexPath) -> NSIndexPath? {
centralManager.stopScan()
connectingPeripheral.append(discoveredDeviceArrayInfo[indexPath.row])
connectPeripheralNow(connectingPeripheral[0])
return indexPath
}
This is where I get it to connect, at this point I select the row which sets the CBPeripheral details of the device to connect to.
connectPeripheralNow looks like this:
func connectPeripheralNow(peripheral: CBPeripheral!){
self.centralManager.connectPeripheral(peripheral, options: nil)
}
didConnectPeripheral and didDiscoverServices looks like this
func centralManager(central: CBCentralManager,didConnectPeripheral peripheral: CBPeripheral)
{
peripheral.delegate = self
peripheral.discoverServices([CBUUID(string: "FFE5")])
print("SUCCESS: Connected to " + peripheral.name!)
}
func peripheral(peripheral: CBPeripheral, didDiscoverServices error: NSError?)
{
if let servicePeripherals = peripheral.services as [CBService]!
{
for servicePeripheral in servicePeripherals
{
print("INFORMATION: Service discovered " + String(stringInterpolationSegment: servicePeripheral.UUID))
peripheral.discoverCharacteristics(nil, forService: servicePeripheral)
}
}
}
Just for the info, I do get a 'SUCCESS: Connected to xxx' message appear which shows that it is connecting. If you need more code, let me know!
What you are mentioning is more of an expected behaviour. BTLE is designed to consume very little amount of energy so it drops the connection as soon as possible. If you do not need a permanent connection then follow Discover --> Connect --> Read/write --> Setup timer --> When timer fires Connect.
If you need a permanent connection, you should subscribe for characteristic which transmits real time data like heart rate application. You would need to implement setNotifyValue:forCharacteristic: method. Read Apple Documentation for more details.
Related
I'm developing app which reads specific characteristics in the background mode. Can this be achieved in the background with selecting the background mode as "Uses Bluetooth LE Accessories" in the plist. Is there any chances of rejecting the app in background if we read particular characteristics of a known service? Reading the characteristics should happen continuously. If we setNotify to "True" will this work in the background. Please provide some valuable suggestions/work around if anyone is aware of it. Thanks in advance.
Can this be achieved in the background with selecting the background mode as "Uses Bluetooth LE Accessories" in the plist.
Yes you can definitely read ble characteristics when your app is in background mode setting the “Uses Bluetooth LE Accessories” background mode in the capabilities tab
Is there any chances of rejecting the app in background if we read particular characteristics of a known service?
If your app needs ble background mode and correctly declares it in the capabilities tab, the app won’t be rejected
Reading the characteristics should happen continuously. If we setNotify to "True" will this work in the background
In order to get notified each time the ble characteristic of your ble peripheral changes its value, you can correctly setNotify to true on the desired characteristic. Each time the characteristic changes its value the peripheral(_:didUpdateStateFor:Error) callback will be triggered and you can get the updated value. Setting the background mode correctly, this callback will be triggered even if your application is in background and your phone is locked.
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic,
error: Error?)
{
print("characteristic: ", characteristic)
guard let string = String(bytes: characteristic.value!, encoding: .utf8) else {
return
}
}
Capabilities -> On Background Modes -> Select External accessory communication & Uses Bluetooth LE accessories
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService,
error: Error?) {
guard let characteristics = service.characteristics else { return }
for characteristic in characteristics {
print(characteristic)
if characteristic.properties.contains(.read) {
print("\(characteristic.uuid): properties contains .read")
peripheral.readValue(for: characteristic)
}
if characteristic.properties.contains(.notify) {
print("\(characteristic.uuid): properties contains .notify")
}
}
}
I'm experimenting with the CoreBluetooth Framework for iOS and I'm facing an issue that I find very Strange.
Once I have a Connected Peripheral, I want to discover it's services - but it fails. Despite searching for and finding Peripherals which offer a specific service. See the code below:
func centralManagerDidUpdateState(central: CBCentralManager) {
if(central.state != .PoweredOn) {
print("Returning due to wrong state: ", central.state)
return;
}
print("Starting peripheral scan")
manager.scanForPeripheralsWithServices(serviceUUID, options: nil)
}
Peripheral Scanning is started and looking for specified serviceUUIDs. In this case: serviceUUIDs = [CBUUID(string: "13333333-3333-3333-3333-333333333337")]. If I change the String, No service is discovered at all (as expected).
func centralManager(central: CBCentralManager, didDiscoverPeripheral peripheral: CBPeripheral, advertisementData: [String : AnyObject], RSSI: NSNumber) {
print("Discovered peripheral: ", peripheral.name)
if(peripheral.name == "PizzaSquat") {
print("Advertising data: ", advertisementData)
print("RSSI: ", RSSI)
activePeripheral = peripheral
print("Connecting to peripheral")
manager.connectPeripheral(peripheral, options: nil)
}
}
On a Linux computer, I have a Bleno instance running which is displaying as a Peripheral with the name "PizzaSquat" (And obviously offers a Service, since it's discovered at all. So when this Peripheral is discovered, I connect to it.
func centralManager(central: CBCentralManager, didConnectPeripheral peripheral: CBPeripheral) {
print("Connected to Peripheral: ", peripheral.name)
if(peripheral.services == nil) {
print("Starting service discovery")
peripheral.delegate = self
peripheral.discoverServices(serviceUUIDs)
} else {
print("Already has services: ")
for service: CBService in peripheral.services! {
print(service)
}
}
}
Once connected (to "PizzaSquat"), I check if it already has services (It doesn't) and start Service discovery. Everything is correct up to this point - But no Services are ever discovered. I expect the below function to be called:
func peripheral(peripheral: CBPeripheral, didDiscoverServices error: NSError?) {
print("Discovered new Service")
for service: CBService in peripheral.services! {
print(service)
}
}
with at least one service, Since the Peripheral shouldn't be discovered at all if it didn't have the specified Service!
I have also tried to call peripheral.discoverServices(nil) to discovery any Service, but still no response.
Could someone help me find the problem?
When you scan for CBPeripheral objects, the peripheral service UUID is obtained from the advertisement packet. The peripheral is basically saying, "Oh yeah, I have this service UUID!" iOS picks that up and passes the CBPeripheral to you.
But the peripheral might not be synced with what is in the advertisement packet. It's a non-binding agreement that the advertisement packet matches what's actually in the peripheral's service/characteristic hierarchy.
So what this means is that it's possible for a peripheral to advertise one service UUID, but actually contain another (or none).
Check out LightBlue on iOS or nRF Control Panel on Android to see if the service/characteristic hierarchy matches what you think it does. In LightBlue you should be able to view the advertisement data and compare it to the services on the peripheral you're connected to.
I am trying to send some data from an iOS device to the HM-10 Bluetooth LE Module connected to an arduino. Problem is after connecting to the module discoverServices doesn't return a characteristic for the service.
func peripheral(peripheral: CBPeripheral, didDiscoverServices error: NSError?) {
if(error != nil) {
print(error?.description)
}
for service in peripheral.services! {
let thisService = service as CBService
print("Service: \(thisService.description)")
print("Characteristic: \(thisService.characteristics)")
}
}
This outputs:
Service: <CBService: 0x137e84ea0, isPrimary = YES, UUID = FFE0>
Characteristic: nil
I am a beginner with this arduino stuff as well as iOS. So any suggestions would be welcome. Maybe there is a way to write to the bluetooth module without knowing the characteristic... I have no idea.
I finally managed to get the answer. Because of my rudimentary understanding of the CoreBluetooth Framework I forgot to call discoverCharacteristics in didDiscoverServices. Well, I am really learning by doing. (I somehow thought discoverServices would call discoverCharacteristics itself.)
I'm developing an app for OS X (10.10) and iOS 8 to exchange some messages with a BLE peripheral. I want my app to find and connect to the peripheral, to send the message to it, and lastly to disconnect, so that the peripheral is free to be accessed from some other device. Everything works fine except for the following particular but still important situation: I scan for BLE devices and I find my device but still I don't connect to it because I have no messages to send. Then I walk away (out of range) or simply I turn the peripheral off. I still have saved in a var my CBPeripheral and I try to connect to it. Nothing happens while I would like the method centralManager:didFailToConnectPeripheral:error: to be called so that I can start to scan again.
centralManager:didConnectPeripheral working properly.
The documentation tells that bluetooth connection requests don't time out so I was wondering what other kinds of problems could lead to a connection failure
func connect(){
if let peripheral = self.peripheralBLE { //Check if the CBPeripheral I was looking for is properly stored
centralManager!.connectPeripheral(peripheral, options: nil)
}
else {
println("Nothing to connect"); //Didn't find any peripheral
}
}
func centralManager(central: CBCentralManager!, didConnectPeripheral peripheral: CBPeripheral!) {
print("connected");
println(peripheral.name);
if (peripheral == nil) {
return;
}
// Create new service class
if (peripheral == self.peripheralBLE) { //if it is the peripheral I was looking for then initialize the service for communication
self.bleService = RFduino(initWithPeripheral: peripheral)
}
connectionStatus = .connected; //update connection status
// Stop scanning for new devices
central.stopScan()
}
func centralManager(central: CBCentralManager!, didFailToConnectPeripheral peripheral: CBPeripheral!, error: NSError!) {
println("Failed to connect peripheral");
if peripheral == self.peripheralBLE{
self.bleService = nil;
self.peripheralBLE = nil;
self.connectionStatus = .disconnected;
}
self.startScanning();
}
Does anybody know how to receive messages through uBudu Mesh Network?
I'm working on an app using uBudu beacons and the general idea is to allow users to send messages to each other through these beacons. I've successfully hooked up iOS-Mesh-SDK as described here: https://github.com/Ubudu/IOS-Mesh-SDK.
There is an example of how to send mesh message to another beacon and it works perfectly, but as for retrieving these messages from beacon to user app I have no idea.
There are methods in MeshBeacon class:
- (void)abortMeshMessage;
- (void)clearMeshMessageQueue;
- (void)setMeshNotification:(BOOL)enable withCompletionBlock:(UMeshBeaconSuccessBlock)completionBlock;
but nothing about retrieving the message.
Any suggestions are highly appreciated!
As you correctly pointed out, the SDK doesn't yet have the method for receiving messages but there is an update of the library coming with support of this feature.
I found maybe brute, but working solution for this problem.
First we need to set ourselves as delegate of BeaconManager
UBUMeshBeaconManager.sharedInstance().delegate = self
In implementation of delegate method, connect to closest beacon and reset its peripheral delegate to self.
func meshManager(meshManager: UBUMeshBeaconManager!, didUpdateVisibleAndConnectableNodes meshNodes: [AnyObject]!) {
UBUMeshBeaconManager.sharedInstance().connectToClosestBeacon({ (meshManager, meshBeacon, userInfo) -> Void in
meshBeacon.peripheral.delegate = self
}, progressBlock: { (meshManager, userInfo) -> Void in
}, failedBlock: { (meshManager, meshBeacon, userInfo, error) -> Void in
})
}
And waiting for characteristics updates in Peripheral Delegate method. All services and characteristics will be set behind the scene by UbuduSDK.
func peripheral(peripheral: CBPeripheral!,
didUpdateValueForCharacteristic characteristic: CBCharacteristic!,
error: NSError!) {
var string = NSString(data: characteristic.value, encoding: NSASCIIStringEncoding)
println(string)
}