我正在尝试在 2 个 iOS 设备之间打开 L2CAP 通道并双向传输数据。其中一个设备充当中心设备,另一个设备充当外围设备。
在外围方面:
我像这样发布 L2CAPChannel:
func peripheralManagerDidUpdateState(_ peripheral: CBPeripheralManager) {
if peripheral.state == .poweredOn {
peripheral.publishL2CAPChannel(withEncryption: false)
}
}
尝试了真假加密。
然后,一旦频道发布,我从 didPublishL2CAPChannel 委托方法中获取 PSM,并创建一个具有包含 PSM 作为其值的特征的服务,并开始宣传它。
在中央一侧:
我扫描外围设备,找到正确的外围设备,连接到它,开始发现服务,然后一旦发现服务,我就会发现特征。我找到了特征,读取了它的值并获得了 PSM。然后我这样做:
self.peripheral.openL2CAPChannel(psm)
然后我在通道打开的委托方法中得到回调并执行以下操作:
func peripheral(_ peripheral: CBPeripheral, didOpen channel: CBL2CAPChannel?, error: Error?) {
guard error == nil else {
print("Couldn't open channel. Error: \(error!.localizedDescription)")
return
}
self.l2capChannel = channel
self.l2capChannel?.inputStream.delegate = self
self.l2capChannel?.outputStream.delegate = self
print("L2CAP channel opened with \(peripheral.name ?? "unknown")")
}
这打印:
L2CAP channel opened with mrsta’s iPad
再次在外围方面:
我在委托方法中得到回调:
func peripheralManager(_ peripheral: CBPeripheralManager, didOpen channel: CBL2CAPChannel?, error: Error?) {
guard error == nil else {
print("Couldn't open channel. Error: \(error!.localizedDescription)")
return
}
self.l2capChannel = channel
self.l2capChannel?.inputStream.delegate = self
self.l2capChannel?.outputStream.delegate = self
print("L2CAP channel opened")
}
这打印:
[CoreBluetooth] No central present! Creating a new object. This shouldn't happen.
L2CAP channel opened
到目前为止,似乎通道是双向打开的。我只是想知道上面印刷品中的信息是什么“......没有中央礼物!......”
过了一会儿,我开始在控制台中收到这样的消息:
[CoreBluetooth] WARNING: Unknown error: 436
[CoreBluetooth] No known channel matching peer <CBPeripheral: 0x2829de120, identifier = 241BAA6F-0BFD-9F5A-1EC9-35A4FD246DF5, name = mrsta’s iPad, state = connected> with psm 192
[CoreBluetooth] WARNING: Unknown error: 431
我不知道这些是什么意思。有什么建议么?
我还在两边都实现了 StreamDelegate 方法:
func stream(_ aStream: Stream, handle eventCode: Stream.Event) {
print("Stream Event occurred: \(eventCode)")
if eventCode == .hasSpaceAvailable {
self.tryToWrite()
}
}
但是上面的委托方法永远不会被调用。我尝试像这样写入输出流(从中心端的 didOpen 通道委托方法调用 tryToWrite):
func tryToWrite() {
let string = "Hello"
let stringData = Data(from: string)
let _ = stringData.withUnsafeBytes { write(stuff: $0, to: self.l2capChannel, withMaxLength: stringData.count) }
}
func write(stuff: UnsafePointer<UInt8>, to channel: CBL2CAPChannel?, withMaxLength maxLength: Int) {
let result = channel?.outputStream.write(stuff, maxLength: maxLength)
print("Write result: \(String(describing: result))")
}
结果是:
Write result: Optional(-1)
根据文档,这意味着写入失败。
请告诉我我错过了什么?打开通道后我得到的错误是什么?写入和读取数据的正确方法是什么?