Question

我正试图通过蓝牙点击按钮发送数据。我可以在打开应用程序时使用以下代码发送数据：

var manager: CBCentralManager!
var device: CBPeripheral?
var characteristics: [CBCharacteristic]?
var serviceUUID = "1234"
var char1 = "FFE1"
let deviceName = "HMSoft"

func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
    DidDiscoverChar.text = "Characteristic found!"

    device = peripheral
    characteristics = service.characteristics

    var value: UInt8 = 1

    let data = NSData(bytes: &value, length: MemoryLayout<UInt8>.size)

    for characteristic in service.characteristics as [CBCharacteristic]!
    {
        if(characteristic.uuid.uuidString == "FFE1")
        {
            device?.writeValue(data as Data, for: characteristic,type: CBCharacteristicWriteType.withoutResponse)

        }
    }
}

但是当我尝试用按钮发送它时：

@IBAction func ledOn(_ sender: AnyObject) {
    var value: UInt8 = 1
    let data = NSData(bytes: &value, length: MemoryLayout<UInt8>.size)

    device?.writeValue(data as Data, for: characteristics,type: CBCharacteristicWriteType.withoutResponse)
}

我收到错误：

无法转换'[CBCharacteristic]类型的值？'预期参数类型'CBCharacteristic'

这似乎是一件容易的事，但作为一个新手，我被卡住了。

编辑:(回应rmaddy的回答）

正如你所建议的，它确实在迭代数组中工作，如下所示。

@IBAction func ledOn(_ sender: AnyObject) {

    var value: UInt8 = 1

    let data = NSData(bytes: &value, length: MemoryLayout<UInt8>.size)


    for characteristic in characteristics as [CBCharacteristic]!
    {

        if(characteristic.uuid.uuidString == "FFE1")
        {
            device?.writeValue(data as Data, for: characteristic,type: CBCharacteristicWriteType.withoutResponse)

        }
    }
}

由于我想作为程序员进行改进，我希望代码更高效。所以我想我可以在按钮功能之外进行迭代，以避免每次按下按钮时的迭代。为了说明我在操场上做了一个简单的例子：

var characteristicFFE1: String = ""
var array = ["r1", "r2", "r3", "FFE1", "r4"]

for uuidString in array {
    if uuidString == "FFE1" {
       characteristicFFE1 = uuidString
    }
}

然后在IBAction中的writeValue中直接使用characteristicFFE1，如下所示：

@IBAction func ledOn(_ sender: AnyObject) {
var value: UInt8 = 1
let data = NSData(bytes: &value, length: MemoryLayout<UInt8>.size)

device?.writeValue(data as Data, for: characteristicsFFE1,type: CBCharacteristicWriteType.withoutResponse)
}

我试图完成上述操作，如下所示：

var characteristicFFE1: CBCharacteristic?

 override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    for characteristic in characteristics as [CBCharacteristic]!  //ERROR HERE
    {

        if(characteristic.uuid.uuidString == "FFE1")
        {
            characteristicFFE1 = characteristic

        }
    }

但我得到错误：线程1：致命错误：在展开Optional值时意外发现nil。

任何人都知道如何解决这个问题？我读过关于选项和解包的内容，但在这里仍然感到困惑。

Answer 1

你的问题在这里

  device?.writeValue(data as Data, for: characteristics,type: CBCharacteristicWriteType.withoutResponse)

您想发送一个您在此处声明的CBCharacteristic类型的可选数组

   var characteristics: [CBCharacteristic]?

虽然参数应该是CBCharacteristic类型的值，您应该在使用之前进行初始化

   var characteristics: CBCharacteristic?

以下是来自Docs

的方法签名

func writeValue（_ data：Data， for characteristic：CBCharacteristic，type：CBCharacteristicWriteType）

使用Swift中的按钮通过蓝牙发送数据

1 个答案: