无法将数据发送到特征 [英] Unable to send data to characteristic

问题描述

当远程设备更改特征值时，我可以在应用程序上收到通知，但是当应用程序更新该值时，远程设备将看不到它.

I am able to get notified on the app when a remote device change the characteristic value, but when the app update the value back, the remote device won't see it.

所以，我知道我的特征是有效的，我也知道其他应用能够写回该特征(实际设备会打印出该特征)

So ,I know my characteristic is valid, i also know that other apps are able to write back to that characteristic (The actual device prints it)

所以问题当然是应用程序中的 .

So problem is of course in the app.

更有趣的是，每个特征都有句柄，每个句柄都有自己的UUID.

Whats more interesting is that every characteristic has handles , which have each its own UUID.

iOS只会让我看到我的特征UUID，无法访问其句柄，尽管每个特征都有2个具有不同UUID的句柄

无论如何，这里我得到回调并尝试写回:

Anyway , here I get the callback and try to write back :

 func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
    print("UPDATE FROM:" , characteristic) //good!
    sendData(data: "check")  //not good
       if characteristic.uuid.uuidString == characteristicUUID {
         if let str = NSString(data: characteristic.value!, encoding: String.Encoding.utf8.rawValue)
         {
            print("BLE:GOT:",str )
            NotificationCenter.default.post(name: Notification.Name(rawValue: "Bluetooth"), object: str)
         }
      }
}

并使用:

  func sendData(data:String)
    {
        if(peripheral != nil)
        {
             //happens for sure
            var bytesData = [UInt8](data.utf8)
            let writeData = NSData (bytes: &bytesData, length: bytesData.count)
             peripheral.writeValue(writeData as Data, for: characteristic, type: CBCharacteristicWriteType.withResponse)
        }
    }

并列出我的特征(打印出1个UUID-没错，我们只有1个，但它有2个具有不同UUID的句柄)

and listing my characteristics ( which prints 1 UUID - thats true we have only 1, but it has 2 handles with different UUID)

  func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
        for charateristic in service.characteristics!
        {
               print("Found CHARACTERISTIC:",charateristic as CBCharacteristic)
        }

推荐答案

您应该检查为您的特性设置了哪些属性.如果设置了CBCharacteristicPropertyWrite，则可以执行带有响应的写操作.如果仅设置了CBCharacteristicPropertyWriteWithoutResponse，则无法在设置了type: CBCharacteristicWriteType.withResponse的情况下执行writeValue.

You should check what properities are set for your characteristic. If CBCharacteristicPropertyWrite is set then write with a response can be executed. If only CBCharacteristicPropertyWriteWithoutResponse is set then you can not execute writeValue with type: CBCharacteristicWriteType.withResponse set.

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