Swift converting BLE characteristic value to a string - ios

Question

I am having an issue that is making no sense. Everything that I am doing I would think is pretty standard for BLE. Anyways, I have a BLE module that I am sending string data from to an iOS application and I am displaying this data on an interface. Since this is my first run using BLE code on an iOS application, I am using the tutorial from adafruit as a guide which can be found here: Adafruit tutorial
As I said, pretty standard stuff. Nothing special here. The code that I have written is able to perform all of the BLE steps. But, when it gets the data, the data is /0/0/0/0/0/0/0/0/0/0/0/0/0/0/0/0. At first, I thought the source on the transmitting side was incorrect. But I opened another test app that lets me see sent BLE data and the data coming in is correctly formatted. It must be an issue with my code. I am not sure why this is happening or what the issue is. I could really use another pair of eyes to see if there is any issue with my code:
My code init code:
required init(parent: ViewController) {
self.parent = parent
self.bluetoothOn = false;
bodyTemperature = 0
airPressure = 0
lightLevel = 0
fanSpeed = 0
Humidity = 0
otherBatteryLevel = 0
wifiStatus = "Good"
super.init()
self.centralManager = CBCentralManager(delegate: self, queue: nil)
// self.periphal = CBPeripheralManager(delegate: self, queue: nil)
}
My didupdateState code:
func centralManagerDidUpdateState(_ central: CBCentralManager) {
if #available(iOS 10.0, *) {
if centralManager.state == CBManagerState.poweredOn{
bluetoothOn = true
self.centralManager.scanForPeripherals(withServices: [ATP_SERVICE_UUID], options: [CBCentralManagerScanOptionAllowDuplicatesKey : false])
}
} else {
// Fallback on earlier versions
}
}
My didDiscover code:
func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
stopScan()
self.blePeripheral = peripheral
self.RSSI = RSSI
self.blePeripheral.delegate = self
centralManager?.connect(blePeripheral, options: nil)
print("Found BLE module")
// blePeripheral.discoverServices([ATP_SERVICE_UUID])
}
my didConnect code:
func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
print("Connected to BLE device")
centralManager?.stopScan()
blePeripheral.delegate = self
blePeripheral.discoverServices([ATP_SERVICE_UUID])
}
My didDiscoverServices code:
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
guard let services = peripheral.services else{
return
}
for service in services{
peripheral.discoverCharacteristics([ATP_UART_WRITE14_UUID, ATP_UART_READ13_UUID, ATP_NOTIFY_UUID], for: service)
}
print("Discovered Services: \(services)")
}
My didDiscoverCharacteristics code:
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
guard let characteristics = service.characteristics else{
return
}
print ("Found \(characteristics.count) characteristics")
for characteristic in characteristics{
if characteristic.uuid.isEqual(ATP_UART_READ13_UUID){
readCharacteristic = characteristic
// blePeripheral.setNotifyValue(true, for: readCharacteristic!)
blePeripheral.readValue(for: characteristic)
print("Rx Characteristic: \(characteristic.uuid)")
}
if(characteristic.uuid.isEqual(ATP_UART_WRITE14_UUID)){
writeCharacteristic = characteristic
print("Tx characteristic: \(characteristic.uuid)")
}
}
}
My didupdateNotificationState code:
func peripheral(_ peripheral: CBPeripheral, didUpdateNotificationStateFor characteristic: CBCharacteristic, error: Error?) {
if(error != nil){
print("Error changing notification state:\(String(describing: error?.localizedDescription))")
} else {
print("Characteristic's value subscribed")
}
if(characteristic.isNotifying){
print("Subscribed. Notification has begun for: \(characteristic.uuid)")
}
}
And lastly, my didUpdateValueFor:
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
if characteristic == readCharacteristic{
// let ASCIIString = NSString(data: characteristic.value!, encoding: String.Encoding.utf8.rawValue)
var stringFromData = String(data: characteristic.value!, encoding: String.Encoding.ascii)
if stringFromData != "" {
let textArray = stringFromData!.components(separatedBy: "\n\r")
for line in textArray{
if line.hasPrefix("bodyTemperature:") {
var splitString = line.characters.split(separator: ":").map(String.init)
bodyTemperature = Float(splitString[1])!
self.delegate?.PQEData(didRecieveData: bodyTemperature)
} else if line.hasPrefix("enclosurePressure:") {
var splitString = line.characters.split(separator: ":").map(String.init)
airPressure = Float(splitString[1])!
self.delegate?.PQEData(didRecieveData: airPressure)
} else if line.hasPrefix("lightLevel:") {
var splitString = line.characters.split(separator: ":").map(String.init)
lightLevel = Float(splitString[1])!
self.delegate?.PQEData(didRecieveData: lightLevel)
} else if line.hasPrefix("humidity:") {
var splitString = line.characters.split(separator: ":").map(String.init)
Humidity = Float(splitString[1])!
self.delegate?.PQEData(didRecieveData: Humidity)
} else if line.hasPrefix("BATT:") {
var splitString = line.characters.split(separator: ":").map(String.init)
otherBatteryLevel = Float(splitString[1])!
self.delegate?.PQEData(didRecieveData: otherBatteryLevel)
} else if line.hasPrefix("fanSpeed:") {
var splitString = line.characters.split(separator: ":").map(String.init)
fanSpeed = Int(splitString[1])!
self.delegate?.PQEData(didRecieveData: fanSpeed)
} else if line.hasPrefix("wifiStatus:") {
var splitString = line.characters.split(separator: ":").map(String.init)
wifiStatus = splitString[1]
self.delegate?.PQEData(didRecieveData: wifiStatus)
}
}
}
}
}
Additional Notes:
1) In the didDiscoverCharaceristics function, I have commented out the call to blePeripheral.setNotifyValue function. That is because on the line for the call to peripheral.discoverCharacteristics call, I am already discovering for the NOTIFY characteristics. I have also tested with the setNotifyValue uncommented and the results are the same.
2) I have a local variable called blePeriphal that stores a reference to the periphal for the ble device. Same applies for writeCharacteristic and readCharacteristic
3) When the blePeripheral.setNotifyValue function was uncommented, the didUpdateNotificationStateFor function was executed. However, the if(error != nil) statement would be true and the error that I would get would be: Error changing notification state:Optional("The request is not supported."). I am not sure if this is related. However, the didUpdateValueFor function would still get executed.
4) The code that is giving me the issue is found in the didUpdateValueFor function and the line is: var stringFromData = String(data: characteristic.value!, encoding: String.Encoding.ascii)
5) Yes, I did try var stringFromData = String(data: characteristic.value!, encoding: String.Encoding.utf8) and var stringFromData = String(data: characteristic.value!, encoding: String.Encoding.utf8.rawValue) and the results were the same. StringFromData is all /0/0/0/0/0/0/0/0/0/0/0/0/0/0/0/0/0/0
Update:
6) So after some testing, I have come across an issue that may be related. The didUpdateValueFor delegate is only being called once and after that, never again. I have verified this by constantly sending a string once every 1/4 second.