How to pass data from delegate method to the observable's onNext method in RxSwift?

Question

I have manager class which will connect and manage the data and state of the Bluetooth device.

The manager class conforms to IWDeviceManagerDelegate and has a method which gives the weight data func onReceiveWeightData(_ device: IWDevice!, data: IWWeightData!).

Once I call listenToWeight() from any controller I want to give the data using Observable.

How I fire an onNext event with the data of onReceiveWeightData method to listenToWeight observable?

Below is the code.

class WeightMachineManager: NSObject {

    func setup() {
        IWDeviceManager.shared()?.delegate = self
        IWDeviceManager.shared()?.initMgr()
    }

    func listenToWeight() -> Observable<IWWeightData> {
        let tag = WeightMachineManager.tag
        if let connectedDevice = connectedDevice {
            IWDeviceManager.shared()?.add(connectedDevice, callback: { (device, code) in
                if code == .success {
                    print("\(tag)[SUCCESS] Device added successfully.")
                } else {
                    print("\(tag)[FAILURE] Failed to add device.")
                }
            })
        } else {
            print("\(tag)[FAILURE] Couldn't find any device to connect.")
        }
    }
}

extension WeightMachineManager: IWDeviceManagerDelegate {
    func onReceiveWeightData(_ device: IWDevice!, data: IWWeightData!) {
        // TODO:- Pass this data in the onNext event of listenToWeight's observable.
    }
}

Answer 1

I've made a lot of assumptions in the below, but the result should look something like this:

class WeightMachineManager {

    var connectedDevice: IWDevice?

    func setup() {
        IWDeviceManager.shared()?.initMgr()
    }

    func listenToWeight() -> Observable<IWWeightData> {
        if let connectedDevice = connectedDevice, let deviceManager = IWDeviceManager.shared() {
            return deviceManager.rx.add(connectedDevice)
                .flatMap { deviceManager.rx.receivedWeightData() } // maybe this should be flatMapLatest or flatMapFirst. It depends on what is calling listenToWeight() and when.
        }
        else {
            return .error(NSError.init(domain: "WeightMachineManager", code: -1, userInfo: nil))
        }
    }
}

extension IWDeviceManager: HasDelegate {
    public typealias Delegate = IWDeviceManagerDelegate
}

class IWDeviceManagerDelegateProxy
    : DelegateProxy<IWDeviceManager, IWDeviceManagerDelegate>
    , DelegateProxyType
    , IWDeviceManagerDelegate {

    init(parentObject: IWDeviceManager) {
        super.init(parentObject: parentObject, delegateProxy: IWDeviceManagerDelegateProxy.self)
    }

    public static func registerKnownImplementations() {
        self.register { IWDeviceManagerDelegateProxy(parentObject: $0) }
    }
}

extension Reactive where Base: IWDeviceManager {

    var delegate: IWDeviceManagerDelegateProxy {
        return IWDeviceManagerDelegateProxy.proxy(for: base)
    }

    func add(_ device: IWDevice) -> Observable<Void> {
        return Observable.create { observer in
            self.base.add(device, callback: { device, code in
                if code == .success {
                    observer.onNext(())
                    observer.onCompleted()
                }
                else {
                    observer.onError(NSError.init(domain: "IWDeviceManager", code: -1, userInfo: nil))
                }
            })
            return Disposables.create()
        }
    }

    func receivedWeightData() -> Observable<IWWeightData> {
        return delegate.methodInvoked(#selector(IWDeviceManagerDelegate.onReceiveWeightData(_:data:)))
            .map { $0[1] as! IWWeightData }
    }
}