How to read value of characteristics?

Question

I'm currently working on BLE device with CoreBluetooth. I can find my device via CBCentralManagerDelegate and connect with my device.

When I want to discover the characteristics of a service, I can get the correct uuid, however, the value of characteristic is nil. Any ideas?

func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
    if error != nil {
        print("ERROR DISCOVERING CHARACTERISTICS: \(error?.localizedDescription)")
        return
    }
    if let characteristics = service.characteristics {

        for characteristic in characteristics {
            print("--------------------------------------------")
            print("Characteristic UUID: \(characteristic.uuid)")
            print("Characteristic isNotifying: \(characteristic.isNotifying)")
            print("Characteristic properties: \(characteristic.properties)")
            print("Characteristic descriptors: \(characteristic.descriptors)")
            print("Characteristic value: \(characteristic.value)")
        }
    }
}

-------------------------------------------------------------------
Characteristic UUID: FA01
Characteristic isNotifying: false
Characteristic properties: CBCharacteristicProperties(rawValue: 26)
Characteristic descriptors: nil
Characteristic value: nil

Another question about properties, according to Bluetooth SIG

Why nRFConnect shows up read, write, notify. But it indeed gets the right value of the characteristic.

Answer 1

read value of characteristics. swift 4

func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
   for newChar: CBCharacteristic in service.characteristics!{

            peripheral.readValue(for: newChar)
        }