Question

尝试使用CoreBluetooth通道在L2CAP中设置数据传输时。我有问题。在发送方，我只需按一下按钮即可触发此功能：

@objc func sendL2CAPInfo() {
    print(#function)
    let value = "Hello L2Cap Stream data...",
    data = Data(value.utf8)
    outPutStream.open()
    print("outPutStream -> \(outPutStream.debugDescription)")
    let bytesWritten = data.withUnsafeBytes { outPutStream.write($0, maxLength: data.count) }
    print("bytesWritten = \(bytesWritten)")
}

执行后，我会在Xcode调试控制台中看到以下内容：

sendL2CAPInfo()
outPutStream -> Optional(<__NSCFOutputStream: 0x282969b00>)
bytesWritten = 26

在接收端，我具有此功能，同时轻按一个按钮即可触发

@objc func receiveL2CAPInfo() {
    print(#function)
    let bufLength = 10
    var buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufLength)
    inPutStream.open()
    let bytesRead = inPutStream.read(buffer, maxLength: bufLength)
    print("bytesRead = \(bytesRead)")
}

在接收方，我也有以下代码：

// StreamDelegate protocol implementation.

func stream(_ aStream: Stream,
            handle eventCode: Stream.Event) {
    print(#function)
    if aStream == inPutStream {print("Input-Stream")}
    if aStream == outPutStream {print("Output-Stream")}

    switch eventCode {
    case Stream.Event.hasBytesAvailable:
        print("Stream.Event.hasBytesAvailable")
        receiveL2CAPInfo()
    case Stream.Event.hasSpaceAvailable:
        print("Stream.Event.hasSpaceAvailable")
    case Stream.Event.openCompleted:
        print("Stream.Event.openCompleted")
    case Stream.Event.endEncountered:
        print("Stream.Event.endEncountered")
    case Stream.Event.errorOccurred:
        print("Stream.Event.errorOccurred")
    default:
        print("Stream.Event.SOME-OTHER-THING-HAPPENED")
    }
}

启动接收应用程序时（正在运行发送应用程序时），我在Xcode调试控制台中看到了这一点：

centralManagerDidUpdateState
centralManager(_:didDiscover:advertisementData:rssi:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-17 13:16:37.168700+0900 CBL2CAPCh_Central[857:127305] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
stream(_:handle:)
Input-Stream
Stream.Event.hasBytesAvailable
receiveL2CAPInfo()
bytesRead = 0
stream(_:handle:)
Input-Stream
Stream.Event.endEncountered

在发送方，事情似乎按预期进行，写入了26个字节。另一方面，在接收端，我们看不到有26个字节。

怎么了？我以前从未使用过L2CAP频道，因此我肯定做得不好，但是我不知道该做什么。任何关于检查或查看地点的建议都将不胜感激。

... 在深入研究该主题之后，这里有一些更多信息。

这是stream（_：handle :)函数的代码：

func stream(_ aStream: Stream,
            handle eventCode: Stream.Event) {
    print(#function)
    if aStream == inPutStream {print("Input-Stream")}
    if aStream == outPutStream {print("Output-Stream")}

    if (aStream != inPutStream) && (aStream != outPutStream)
    {print("Some-other-Stream")}

    switch eventCode {
    case Stream.Event.hasBytesAvailable:
        print("Stream.Event.hasBytesAvailable")
    case Stream.Event.hasSpaceAvailable:
        print("Stream.Event.hasSpaceAvailable")
    case Stream.Event.openCompleted:
        print("Stream.Event.openCompleted")
    case Stream.Event.endEncountered:
        print("Stream.Event.endEncountered")
    case Stream.Event.errorOccurred:
        print("Stream.Event.errorOccurred")
        if let error = aStream.streamError {
            print("Error:\n\t\(error.localizedDescription)")
        }
    default:
        print("Stream.Event.SOME-OTHER-THING-HAPPENED")
    }
}

启动中央应用程序后，在尝试编写任何内容之前，在调试器中可以看到以下内容：

centralManagerDidUpdateState
centralManager(_:didDiscover:advertisementData:rssi:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:32:14.840892+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
stream(_:handle:)
Input-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Output-Stream
Stream.Event.hasSpaceAvailable
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:32:28.521320+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
stream(_:handle:)
Input-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Output-Stream
Stream.Event.hasSpaceAvailable
2019-01-18 13:32:28.523746+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:32:38.948090+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
2019-01-18 13:32:38.949889+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:32:49.278142+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
2019-01-18 13:32:49.280093+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:32:59.739338+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
2019-01-18 13:32:59.741111+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:33:10.567965+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
2019-01-18 13:33:10.569722+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:33:21.404162+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
2019-01-18 13:33:21.406243+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:33:32.147567+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
2019-01-18 13:33:32.148884+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:33:42.788001+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
2019-01-18 13:33:42.789921+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
2019-01-18 13:33:53.734140+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 431
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
2019-01-18 13:33:53.736063+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x281bc4a00, identifier = D73B08A0-E9BB-483B-8078-4A7F992E7565, name = Michel’s iPad, state = connected> with psm 192
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
2019-01-18 13:34:04.231561+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 436
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
2019-01-18 13:34:14.861939+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 436
centralManager(_:didDisconnectPeripheral:error:)
centralManager(_:didConnect:)
peripheral(_:didOpen:error:)
stream(_:handle:)
Some-other-Stream
Stream.Event.hasSpaceAvailable
stream(_:handle:)
Output-Stream
Stream.Event.openCompleted
stream(_:handle:)
Input-Stream
Stream.Event.openCompleted
stream(_:handle:)
Some-other-Stream
Stream.Event.hasBytesAvailable
2019-01-18 13:34:25.472075+0900 CBL2CAPCh_Central[571:80355] [CoreBluetooth] WARNING: Unknown error: 436

Answer 1

您应该在连接频道时打开流，而不是在点击按钮时尝试打开流。然后，您可以使用流委托hasBytesAvailable事件来确定要读取的字节。

在当前运行循环上安排流很重要。

例如，要在CBCentral上打开流：

func peripheral(_ peripheral: CBPeripheral, didOpen channel: CBL2CAPChannel?, error: Error?) {
    if let error = error {
        print("Error opening l2cap channel - \(error.localizedDescription)")
        return
    }
    guard let channel = channel else {
        return
    }
    print("Opened channel \(channel)")
    self.channel = channel
    channel.inputStream.delegate = self
    channel.outputStream.delegate = self
    print("Opened channel \(channel)")
    channel.inputStream.schedule(in: RunLoop.current, forMode: .default)
    channel.outputStream.schedule(in: RunLoop.current, forMode: .default)
    channel.inputStream.open()
    channel.outputStream.open()
}

然后处理接收到的数据：

 func stream(_ aStream: Stream, handle eventCode: Stream.Event) {
     switch eventCode {
        case Stream.Event.openCompleted:
            print("Stream is open")
        case Stream.Event.endEncountered:
            print("End Encountered")
        case Stream.Event.hasBytesAvailable:
            print("Bytes are available")
            if let iStream = aStream as? InputStream {
                let bufLength = 1024
                let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufLength)
                let bytesRead = iStream.read(buffer, maxLength: bufLength)
                print("bytesRead = \(bytesRead)")
                if let string = String(bytesNoCopy: buffer, length: bytesRead, encoding: .utf8, freeWhenDone: false) {
                    print("Received data: \(string)")
                }
            }
        case Stream.Event.hasSpaceAvailable:
            print("Space is available")
        case Stream.Event.errorOccurred:
            print("Stream error")
        default:
            print("Unknown stream event")
    }
}

我的完整工作示例可在此处找到：https://github.com/paulw11/L2CapDemo

通过CoreBluetooth / L2CAP通道传输数据

1 个答案: