iOS BLE problem didUpdateValueForCharacteristic not called ios14 - ios

Question

We have a peripheral device and I am trying to connect it with iOS device. It was working fine with Swift 3.0 But when I am trying to convert it in Swift 5.0 it did not work. It is working perfectly fine with Android device. So it is not an issue of hardware.
I have successfully connected and also discovered services and characteristics. My characteristics give me notify property only, I set that to true which also triggered the didupdateNotificationStateFor delegate method and it showed the characteristic.isnotifying as true. Which meant my subscription is successful. The only problem I am facing is didUpdateValueForCharacteristic is never been called. My code is as under.
extension HRMViewController: CBPeripheralDelegate {
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
guard let services = peripheral.services else { return }
for service in services {
print(service)
peripheral.discoverCharacteristics(nil, for: service)
// break
}
}
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 transferCharacteristic.properties.contains(.notify) {
print("\(characteristic.uuid): properties contains .notify")
peripheral.setNotifyValue(true, for: characteristic)
}
if characteristic.properties.contains(.write){
}
}
}
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
switch characteristic.uuid {
case aCBUUID:
lblResult.text = "UUID: \(characteristic.uuid) Value = \(String(describing: characteristic.value))"
case bCBUUID:
lblResult2.text = "UUID: \(characteristic.uuid) Value = \(String(describing: characteristic.value))"
case f:
print("CORRECT Characteristic UUID: \(characteristic.uuid)")
print(characteristic.value ?? "no value")
default:
print("Unhandled Characteristic UUID: \(characteristic.uuid)")
print(characteristic.value ?? "no value")
}
}
func peripheral(_ peripheral: CBPeripheral, didUpdateNotificationStateFor characteristic: CBCharacteristic, error: Error?) {
if error != nil {
print("Error ==",error?.localizedDescription ?? "")
}
print("updateNotification: \(characteristic.isNotifying)")
}
Any help in this regard is highly appreciated.