如何读取特征值？

Question

我目前正在使用 CoreBluetooth 开发 BLE 设备。我可以通过找到我的设备CBCentralManagerDelegate并连接到我的设备。

当我想发现一个服务的特性时，我可以得到正确的uuid，但是特性的值是nil。有任何想法吗？

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

根据蓝牙 SIG 的说法，关于属性的另一个问题

为什么nRFConnect出现read, write, notify. 但它确实得到了特征的正确值。

Answer 1

读取特征值。迅捷4

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

            peripheral.readValue(for: newChar)
        }