iOS/Swift/CoreBluetooth Ble Notifications not working - ios

Question

I have a problem where I connect to a peripheral and set notify value to true correctly but I can't get the value. I am following the next steps.
1 - I connect to peripheral
2 - I discover services
3 - I discover characteristics for services
4 - I activate notifications for a specific characteristic
override func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
if characteristic.uuid == historicCharacteristicCBUUID && characteristic.properties.contains(.notify) {
print("\(characteristic.uuid): properties contains .notify")
if hasWritenOnHistoric == false {
peripheral.setNotifyValue(true, for: characteristic)
}
}
}
5 - I wait to the delegate and then write on the characteristic to tell the peripheral to start sending data
override func peripheral(_ peripheral: CBPeripheral, didUpdateNotificationStateFor characteristic: CBCharacteristic, error: Error?) {
print(characteristic)
if error == nil {
print("TRUE")
if characteristic.uuid == historicCharacteristicCBUUID && characteristic.isNotifying == true {
writeOnHistory(peripheral: peripheral, characteristic: characteristic)
} else {
print("no ha cambiado su estado")
}
}
}
6 - Write on peripheral
func writeOnHistory(peripheral: CBPeripheral, characteristic: CBCharacteristic) {
if characteristic.uuid == historicCharacteristicCBUUID {
hasWritenOnHistoric = true
var bitesArray: [UInt8] = [0x01, 0x05]
for _ in 1...16 {
bitesArray.append(0x00)
}
print(bitesArray.count)
print(bitesArray)
let data = Data(bytes: bitesArray)
peripheral.writeValue(data, for: characteristic, type: .withResponse)
}
}
7 - This delegate is only called once and with empty data [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00](in Android is working fine getting all the data from the peripheral)
override func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
if let data = characteristic.value {
print(data)
}
}
Is there something I am missing?
Thanks in advance!

Answer 1

You will not observe if your value is changed unless you call didWriteValueFor.
func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
if characteristic.uuid == myCharacteristic {
self.bluetoothManager.readValueForCharacteristic(characteristic: myCharacteristic)
}
}