BLE 更改要写入的 UUID 特征

Question

我对使用 Swift 进行编码还很陌生，所以我希望有人能帮助我给出一个简单的答案。

我基本上是在尝试将特征 UUID 发送到写入函数，然后切换写入函数以写入该 UUID。它只会继续使用我原来的那个。是否有捷径可寻？我发现了所有外围设备、服务和特征，并且已经连接到正确的设备。我只是无法让它切换到正确的特征 UUID。任何帮助都是极好的！我是一名 firmware/hardware 开发人员，所以 Swift 和 Xcode 对我来说还不是日常用品。

func writePosition(position: UInt16, characteristicUUID: CBUUID) {

    var position_low: UInt8 = 0
    var position_high: UInt8 = 0
    var position16: UInt16 = 0;

    position_low  = (UInt8) (position)  // (position)
    position_high = (UInt8)((position >> 8))


    // See if characteristic has been discovered before writing to it
    if self.positionCharacteristic == nil {
        return
    }
    var bytes:[UInt8] = [0x00, 0x00]

    bytes[1] = 0x01  //low byte is [1], high byte is [0] so reversed from LightBlue app

    bytes[1] = position_low  //low byte is [1], high byte is [0] so reversed from LightBlue app
    bytes[0] = position_high  //low byte is [1], high byte is [0] so reversed from LightBlue app



    let uuidsForBTService:  [CBUUID] = [characteristicUUID]
    //new code to try and set the correct UUID automatically
    for service in peripheral!.services
    {
        if service.UUID == BLEServiceUUID
        {
          peripheral!.discoverCharacteristics(uuidsForBTService, forService: service as! CBService)
        }

    }


    //find the correct characteristic to set to and then write to it
    //go through each characteristic and look at its UUID then if it matches, set us to that one so we write to it later on
    for characteristic in self.peripheral!.services {
        if characteristic.UUID == characteristicUUID//Position1PWMCharUUID
        {
            self.positionCharacteristic = (characteristic as! CBCharacteristic)
            peripheral!.setNotifyValue(true, forCharacteristic: characteristic as! CBCharacteristic)

            // Send notification that Bluetooth is connected and all required characteristics are discovered
            self.sendBTServiceNotificationWithIsBluetoothConnected(true)
        }
    }

    //end of code to set the UUID


    // Need a mutable var to pass to writeValue function
    //var positionValue = position
   //let data = NSData(bytes: &positionValue, length: sizeof(UInt16))
    let data = NSData(bytes: bytes, length: 2)
   self.peripheral?.writeValue(data, forCharacteristic: self.positionCharacteristic, type: CBCharacteristicWriteType.WithResponse)



}

Answer 1

请记住，在第二个 for 循环中，您正在寻找 CBCharacteristic 的地方，您仍在迭代外围设备的服务和不是您的 ble 服务的特征（外围设备有服务，服务有特征）。

下面的代码就是得到你需要的CBCharacteristic

var theService: CBService?

// Find service
for service in peripheral.services as! [CBService] {
    if service.UUID == BLEServiceUUID {
        theService = service

        break
    }
}

var theCharacteristic: CBCharacteristic?

// Find characteristic
for characteristic in theService?.characteristics as! [CBCharacteristic] {
    if characteristic.UUID == characteristicUUID {
        theCharacteristic = characteristic

        break
    }
}

// Write
if let characteristic = theCharacteristic {
    peripheral.writeValue(data, forCharacteristic: characteristic, type: .WithResponse)
}

在您的代码中，您总是写入 self.positionCharacteristic。只需将您的数据写入您刚刚找到的CBCharacteristic。

此外，如果您需要更多帮助，我写了一个简单的 swift class 来管理中央连接、读取和写入任务。

希望对您有所帮助！

BLE 更改要写入的 UUID 特征

BLE changing which UUID characteristic to write to

core-bluetooth

bluetooth-lowenergy