如果我 readValue，iOS BLE 外设 writeValue 不起作用

Question

我在 MacOS 应用程序中有一个外围设备，在 iOS 应用程序中有一个中心设备。中央有如下代码:

func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
    for characteristic in service.characteristics! {
        print(characteristic.uuid)
        switch characteristic.uuid {
        case bleCharacteristics().read:
            print("Read it!")
            peripheral.setNotifyValue(true, for: characteristic)
            peripheral.readValue(for: characteristic)
            break
        case bleCharacteristics().write:
            print("Write to it!")
            peripheral.writeValue("Heyooo".data(using: .utf8)!, for: characteristic, type: .withResponse)
            break
        case bleCharacteristics().notify:
            print("Subscribe to it!")
            peripheral.setNotifyValue(true, for: characteristic)
            break
        default:
            print("Got to the characteristics default somehow")
        }
    }
}

readValue 工作正常，但 writeValue 根本不起作用(因为在 PeripheralManager 的 didReceiveWriteRequests 中永远不会被调用)。如果我注释掉 readValue 那么 writeValue 就可以正常工作。文档中没有任何地方说 readValue 是阻塞异步操作或类似的操作，所以我不知道发生了什么。

如果有人知道我做错了什么，我将非常感激。

Answer 1

有时候你必须发布问题才能找到答案。在我的外围代码中，我有:

func peripheralManager(_ peripheral: CBPeripheralManager, didReceiveRead request: CBATTRequest) {
    let response = "Hey there".data(using: .utf8)
    request.value = response
    peripheral.updateValue(response!, for: characteristics![0] as! CBMutableCharacteristic, onSubscribedCentrals: [request.central])
}

由于 updateValue 方法，它正在“读取”值，但没有关闭读取请求。添加行:

peripheral.respond(to: request, withResult: .success)

是响应读取请求的正确方法，并使 writeValue 按预期工作。正确的外围代码:

func peripheralManager(_ peripheral: CBPeripheralManager, didReceiveRead request: CBATTRequest) {
    let response = "Hey there".data(using: .utf8)
    request.value = response
    peripheral.respond(to: request, withResult: .success)
}