我正在尝试通过单击按钮通过蓝牙发送数据。使用以下代码打开应用程序时,我可以发送数据:
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)
}
}
}
但是当我尝试使用按钮发送它时:
@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:
Cannot convert value of type '[CBCharacteristic]?' to expected argument type 'CBCharacteristic'
这似乎是一项简单的任务,但作为一个新手,我被困住了。
编辑:(对 rmaddy 回答的回应)
正如您所建议的,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,我希望代码更高效。所以我想我可以在按钮函数之外进行迭代,以避免每次按下按钮时都进行迭代。为了说明我在 Playground 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
}
}
然后像这样在 IBAction 的 writeValue 中直接使用 characteristicFFE1:
@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)
}
我尝试完成上面的操作,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:Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value.
有人知道如何解决这个问题吗?我阅读了有关可选值和展开的内容,但在这里仍然感到困惑。
最佳答案
你的问题在这里
device?.writeValue(data as Data, for: characteristics,type: CBCharacteristicWriteType.withoutResponse)
你想发送一个你在这里声明的 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对其进行初始化
var characteristics: CBCharacteristic?
这是来自 Docs 的方法签名
func writeValue(_ data: Data, for characteristic: CBCharacteristic,type:CBCharacteristicWriteType)
关于swift - 使用 Swift 中的按钮通过蓝牙发送数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/48844845/