使用 Swift 中的按钮通过蓝牙发送数据

Question

我正在尝试通过单击按钮通过蓝牙发送数据。我可以在使用以下代码打开应用程序时发送数据：

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)
}

我得到错误：

无法转换类型“[CBCharacteristic]？”的值到预期的参数类型'CBCharacteristic'

这似乎是一项简单的任务，但作为一个新手，我被卡住了。

编辑：（回复 rmaddy 的回答）

按照您的建议，它确实可以遍历数组，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)

        }
    }
}

作为一名程序员，我想提高自己，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)
}

我尝试完成上面的，如下图：

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

        }
    }

但我收到错误：线程 1：致命错误：在展开可选值时意外发现 nil。

有人知道如何解决这个问题吗？我已经阅读了有关可选和展开的信息，但在这里仍然感到困惑。

Answer 1

你的问题来了

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

您想发送您在此处声明的CBCharacteristic 类型的可选数组

   var characteristics: [CBCharacteristic]?

虽然参数应该是 CBCharacteristic 类型的值，但您应该在像这样使用之前初始化它

   var characteristics: CBCharacteristic?

这是来自Docs的方法签名

func writeValue(_data: 数据, 对于特征：CBCharacteristic，类型：CBCharacteristicWriteType）