RxSwift网络琏式请求总结

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RxSwift是在 Apple 推出 Swift 后， ReactiveX 推出 Reactive Extensions 系列一个实现库。下面介绍工作中使用RxSwift解决异步网络请求场景的实践。

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业务场景为根据当前定位位置请求附近公交、地铁、水巴数据。根据右侧的筛选项筛选出不同的数据，进行请求。

创建数据事件源Observable

• 请求地铁网络数据

func searchSubwayData(_ location: CLLocationCoordinate2D, _ isUserLocation: Bool = false) -> Observable<Bool> {
    return Observable<Bool>.create { [weak self] (observer) -> Disposable in
        let send = SubwaySendModel()
        send.latitude = location.latitude
        send.longitude = location.longitude
        send.range = 500
        SubwayNetwork.This.doTask(SubwayNetwork.CMD_getByCoord, data: send, controller: nil, success: {[weak self] (response: SubwayResponseModel?) in
            observer.onCompleted()
            guard let resp = response else {return}
            guard resp.line.count > 0 else {return}
            if isUserLocation == true {
                self?.subWayResponseModel = nil
                self?.subWayResponseModel = response
            }
            guard resp.station.count > 0 else {return}
            guard let stations: [SubwayStationModel] = (resp.station as NSArray).jsonArray() else {return}
            
            for model in stations {
                let annotation = RyHomeMAPointAnnotation(.subway)
                annotation.title = model.name
                annotation.coordinate = JZLocationConverter.wgs84(toGcj02: CLLocationCoordinate2D.init(latitude: CLLocationDegrees(model.latitude), longitude: CLLocationDegrees(model.longitude)))
                let nearStationModel = RyHomeNearStationModel()
                nearStationModel.name = model.name
                nearStationModel.desc = model.lines
                let nlocation = CLLocation.init(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude)
                nearStationModel.sid = "\(model.id)"
                nearStationModel.mtype = .subway
                if let userLocation = self?.mapView.userLocation.location {
                    nearStationModel.locationDistance = userLocation.distance(from: nlocation)
                }
                nearStationModel.location = nlocation
                annotation.mStationModel = nearStationModel
                self?.nearStationModelArr.append(nearStationModel)
                self?.subwayAnnotations.append(annotation)
            }
            self?.mapView.addAnnotations(self?.subwayAnnotations)
            
            }, error: { [weak self] (err, msg) in
                self?.subWayResponseModel = nil
                observer.onError(TestError.test)
            }, com: nil, showWait: false)
        
        return Disposables.create()
    }
}

• 请求水巴网络数据

func searchBoatData(_ location: CLLocationCoordinate2D, _ isUserLocation: Bool = false) -> Observable<Bool> {
    return Observable<Bool>.create { [weak self] (observer) -> Disposable in
        let send = WaterBusSendModel()
        send.latitude = location.latitude
        send.longitude = location.longitude
        send.range = 500
        
        WaterBusNetWork.This.doArrayTask(WaterBusNetWork.CMD_getByCoord, data: send, controller: nil, success: { [weak self] (response: [ShuiBaStationModel]?) in
            observer.onCompleted()
            guard let stations = response else {return}
            guard stations.count > 0 else {return}
            if isUserLocation == true {
                self?.shuibaResponseArr = nil
                self?.shuibaResponseArr = stations
            }
            
            for model in stations {
                let annotation = RyHomeMAPointAnnotation(.boat)
                annotation.title = model.n
                annotation.coordinate = JZLocationConverter.wgs84(toGcj02: CLLocationCoordinate2D.init(latitude: CLLocationDegrees(model.la), longitude: CLLocationDegrees(model.lo)))
                let nearStationModel = RyHomeNearStationModel()
                nearStationModel.name = model.n
                nearStationModel.desc = "途径\(model.rcount ?? "0")条线路"
                let nlocation = CLLocation.init(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude)
                nearStationModel.sid = model.i
                nearStationModel.mtype = .boat
                if let userLocation = self?.mapView.userLocation.location {
                    nearStationModel.locationDistance = userLocation.distance(from: nlocation)
                }
                nearStationModel.location = nlocation
                annotation.mStationModel = nearStationModel
                self?.nearStationModelArr.append(nearStationModel)
                self?.boatAnnotations.append(annotation)
            }
            self?.mapView.addAnnotations(self?.boatAnnotations)
            
            }, error: { [weak self] (_, _) in
                self?.shuibaResponseArr = nil
                observer.onError(TestError.test)
            }, com: nil, showWait: false)
        
        return Disposables.create()
    }
}

• 请求公交站网络数据

func searchBusStationData(_ location: CLLocationCoordinate2D) -> Observable<Bool> {
    return Observable<Bool>.create { [weak self] (observer) -> Disposable in
        let send = SendGetFullStationByCoord()
        send.latitude = location.latitude
        send.longitude = location.longitude
        send.range = 500
        send.withLCheck = true
        BusNetWork.This.doArrayTask(BusNetWork.CMD_getByCoord, data: send, controller: self, success: { (responseObj:[GetFullStationByCoord]?) in
            observer.onCompleted()
            guard let stations = responseObj else {return}
            guard stations.count > 0 else {return}
            
            for model in stations {
                let annotation = RyHomeMAPointAnnotation(.busStation)
                annotation.title = model.n
                annotation.coordinate = JZLocationConverter.wgs84(toGcj02: CLLocationCoordinate2D.init(latitude: CLLocationDegrees(model.la), longitude: CLLocationDegrees(model.lo)))
                let nearStationModel = RyHomeNearStationModel()
                nearStationModel.name = model.n
                nearStationModel.desc = "途径\(model.c)条线路"
                let nlocation = CLLocation.init(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude)
                nearStationModel.sid = model.i
                nearStationModel.mtype = .busStation
                nearStationModel.linec = Int(model.c)
                if let userLocation = self?.mapView.userLocation.location {
                    nearStationModel.locationDistance = userLocation.distance(from: nlocation)
                }
                nearStationModel.location = nlocation
                annotation.mStationModel = nearStationModel
                self?.nearStationModelArr.append(nearStationModel)
                self?.busStationAnnotations.append(annotation)
            }
            self?.mapView.addAnnotations(self?.busStationAnnotations)
            
        }, error: { (_, _) in
            observer.onError(TestError.test)
        }, com: nil, showWait: false)
        
        return Disposables.create()
    }
    
}

代码中Observable<Bool>.create { }是创建一个被观察者，observer.onCompleted()是网络数据请求回来，当前观察者发送完成信号，开始处理下一个事件，observer.onError(TestError.test)是网络请求失败，发送失败信号，使整个事件序列重新开始请求。

Observable就是可被观察的，是事件源，可以被订阅，上面创建了三个Observable，下面我们可以通过concat，把创建的三个事件联合起来一起被订阅。

联合订阅事件源

let disposeBag = DisposeBag()
func getData(_ isUserLocation: Bool = false) {
    ryHomeRightCategoryView.updateFilterIcon(filterType)
    
    guard let location = movedLocationCoordinate else {return}
    
    mapView.removeOverlays(mapView.overlays)
    addOverlay(location)
    mapView.removeAnnotations(subwayAnnotations)
    mapView.removeAnnotations(boatAnnotations)
    mapView.removeAnnotations(busStationAnnotations)
    subwayAnnotations.removeAll()
    boatAnnotations.removeAll()
    busStationAnnotations.removeAll()
    nearStationModelArr.removeAll()
    
    let wgsLocation = JZLocationConverter.gcj02(toWgs84: location)
    
    let symbol1 = searchSubwayData(wgsLocation)
    let symbol2 = searchBoatData(wgsLocation)
    let symbol3 = searchBusStationData(wgsLocation)
    
    var symbols: Observable<Observable<Bool>>? = nil
    if filterType == .subway {
        symbols = Observable.of(symbol1)
    }
    else if filterType == .boat {
        symbols = Observable.of(symbol2)
    }
    else if filterType == .bus {
        symbols = Observable.of(symbol3)
    }
    else if filterType == .all {
        symbols = Observable.of(symbol1, symbol2, symbol3)
    }
    symbols?.concat().retry(2).subscribe().addDisposableTo(disposeBag)
}

这个方法，通过concat把几个事件源联合起来进行订阅，就实现了多个网络的链式顺序请求。

• 创建了地铁、水巴、公交站台三个被观察者的对象，这样方便后面进行筛选数据。

let symbol1 = searchSubwayData(wgsLocation)
let symbol2 = searchBoatData(wgsLocation)
let symbol3 = searchBusStationData(wgsLocation)

• 创建事件源序列对象var symbols: Observable<Observable<Bool>>? = nil 根据当前的筛选类型filterType，给symbols进行赋值

var symbols: Observable<Observable<Bool>>? = nil
if filterType == .subway {
    symbols = Observable.of(symbol1)
}
else if filterType == .boat {
    symbols = Observable.of(symbol2)
}
else if filterType == .bus {
    symbols = Observable.of(symbol3)
}
else if filterType == .all {
    symbols = Observable.of(symbol1, symbol2, symbol3)
}

• 联合订阅事件，把当前事件添加到释放池disposeBag，方便当前页面被释放后，被订阅的事件可以被释放。

symbols?.concat().retry(2).subscribe().addDisposableTo(disposeBag)

参考

• RxSwift入坑解读-你所需要知道的各种概念
• RxSwift 入坑手册 Part0 - 基础概念