iOS:写入描述符不允许写入

Question

我正在为 Central 和 Peripheral 示例构建简单的应用程序，

中央代码工作正常，因为当 Android 充当外围设备时，我能够编写特征和描述符，

但是当iOS作为Peripheral时，我无法写描述符，

我收到错误域=CBATTErrorDomain 代码=3“不允许写入。” UserInfo={NSLocalizedDescription=不允许写入。}

我相信，我错过了一些东西，知道我做错了什么吗？

//Peripheral Code
           transferCharacteristic = CBMutableCharacteristic(
                type: transferCharacteristicUUID,
                properties: [.indicate,.writeWithoutResponse,.read],
                value: nil,
                permissions: [.writeable,.readable]
            )
            
            let userDesc = CBMutableDescriptor(type: userCharacteristicUUID, value: "Used to send commands")
            
            transferCharacteristic?.descriptors = [userDesc]
            
            // Then the service
            transferService = CBMutableService(
                type: transferServiceUUID,
                primary: true
            )
            
            // Add the characteristic to the service
            transferService?.characteristics = [transferCharacteristic!]
            peripheralManager!.add(transferService!)
            peripheralManager!.startAdvertising([CBAdvertisementDataServiceUUIDsKey : [transferServiceUUID],CBAdvertisementDataLocalNameKey : "Broadcaster"])


//Central Code where it throw error
 /** This callback lets us know more data has arrived via notification on the characteristic
     */
    func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
    var clientDes : CBDescriptor?
   
    for desc in characteristic.descriptors!{
        if desc.uuid.uuidString  == CBUUIDCharacteristicUserDescriptionString {
            clientDes = desc
        }
    }
 let sendValue:[UInt8] = [0x02, 0x00]
        let data = NSData(bytes: sentValue, length: 2)
        peripheral.writeValue(data as Data, for: clientDes!)
}

//Here I am getting the log
    func peripheral(_ peripheral: CBPeripheral, didWriteValueFor descriptor: CBDescriptor, error: Error?) {
        print("wrote to \(String(describing: error))")
    }

Answer 1

尽管 CBPeripheral 提供了 writeValue(data:Data, descriptor: CBDescriptor) 方法并且文档仅声明您不能写入 CBUUIDClientCharacteristicConfigurationString< 类型的描述符，CBPeripheralManagerDelegate 不提供任何方式来通知写入描述符。

因此，您无法从 CBPeripheralManager 提供的外围设备写入任何描述符。

您应该简单地创建另一个要写入的特征。