一旦找到匹配项，如何停止 RxSwift ble 扫描器？

Question

我有一个 ble 扫描仪，可以正常工作，看起来像这样：

func scan(serviceId: String) -> Observable<[BleHandler.BlePeripheral]> {
    knownDevices = []
    return waitForBluetooth()
        .flatMap { _ in self.scanForPeripheral(serviceId: serviceId) }
        .map { _ in self.knownDevices }
}

private func waitForBluetooth() -> Observable<BluetoothState> {
    return self.manager
        .observeState()
        .startWith(self.manager.state)
        .filter { [=10=] == .poweredOn }
        .take(1)
}

然后在 viewModel class 中过滤来自 core data:

的匹配项

func scanAndFilter() -> Observable<[LocalDoorCoreDataObject]> {
        let persistingDoors: [LocalDoorCoreDataObject] = coreDataHandler.fetchAll(fetchRequest: NSFetchRequest<LocalDoorCoreDataObject>(entityName: "LocalDoorCoreDataObject"))

    return communicationService
        .scanForDevices(register: false)
        .map{ peripherals in
            print(" THIS WILL GO ON FOR ETERNITY", peripherals.count)
            self.knownDevices = peripherals
            return persistingDoors
                .filter { door in peripherals.contains(where: { [=11=].identifier.uuidString == door.dPeripheralId }) }
        }
}

并且在 view 扫描完成后我想连接：

private func scanAndConnect(data: LocalDoorCoreDataObject) {
    viewModel.scanRelay().subscribe(
        onNext: {
            print("SCANNED NAME", [=12=].first?.dName)},
        onCompleted: {
            print("COMPLETED SCAN")
            self.connectToFilteredPeripheral(localDoor: data)
    }).disposed(by: disposeBag)
}

它永远不会到达 onCompleted，因为即使在找到 filtered core data 匹配后，它也会一直扫描下去。在 Apple 的框架 coreBluetooth 中，我可以在找到我想要的内容后简单地调用 manager.stopScan()，但是 Rx 对应的框架似乎不可用。它如何适用于 RxSwift

Answer 1

您可以创建一个新的 Observable 来查找设备，然后在找到您要查找的设备后立即完成。这将是这样的：

func scanAndFilter() -> Observable<[LocalDoorCoreDataObject]> {
        return Observable.deferred { in
            let persistingDoors: [LocalDoorCoreDataObject] = coreDataHandler.fetchAll(fetchRequest: NSFetchRequest<LocalDoorCoreDataObject>(entityName: "LocalDoorCoreDataObject"))

            return communicationService
                .scanForDevices(register: false)
                .filter { /* verify if the device(s) you're looking for is/are in this list */ }
                .take(1)
        }
    }

filter operator will make sure that only lists that contain the device you're looking for are passed on and the take(1) operator 将获取第一个发出的值并立即完成。

deferred 调用确保第一行中执行的获取请求不会在您调用 scanAndFilter() 时执行，而只会在有人实际订阅生成的 Observable 时执行。

Answer 2

如果只想让一个事件退出过滤算子，那么就用.take(1)。 Observable 将在发出单个值后关闭。如果BLE函数写对了，Disposable处理时会调用stopScan()

我不知道为什么另一个答案说“始终确保将 return Observables 的所有函数包装到 .deferred 中。自 2015 年以来我一直在使用 RxSwift，并且我已经只需要延迟一次。当然不是每次我调用 returned 一个 Observable 的函数时。

一旦找到匹配项，如何停止 RxSwift ble 扫描器？

How do I stop RxSwift ble scanner once it has found a match?

ios

bluetooth-lowenergy

swift

rx-swift

rxbluetooth