如何在带有RxSwift的驱动程序上使用flatMapLatest
每当我的用户位置发生变化时,我都试图从网络中获取一些数据如何在带有RxSwift的驱动程序上使用flatMapLatest,swift,reactive-programming,rx-swift,rx-cocoa,Swift,Reactive Programming,Rx Swift,Rx Cocoa,每当我的用户位置发生变化时,我都试图从网络中获取一些数据 struct CityService { private init() {} static let shared = CityService() lazy var nearbyCities: Driver<[City]> = { return GeolocationService.instance.location .flatMapLatest({ coordinate in
struct CityService {
private init() {}
static let shared = CityService()
lazy var nearbyCities: Driver<[City]> = {
return GeolocationService.instance.location
.flatMapLatest({ coordinate in
let location = CLLocation(latitude: coordinate.latitude, longitude: coordinate.longitude)
return CityService.shared.fetchNearbyCitiesFor(location)
}).asDriver(onErrorJustReturn: [])
}()
func fetchNearbyCitiesFor(_ location: CLLocation) -> Observable<[City]> {
return Observable.create { observer in
let disposable = Disposables.create()
// Mock a fetch from the network:
let cities = [City(name: "Amsterdam"), City(name: "Berlin")]
observer.onNext(cities)
observer.on(.completed)
return disposable
}
}
}
class GeolocationService {
static let instance = GeolocationService()
private (set) var location: Driver<CLLocationCoordinate2D>
}
// from: https://github.com/ReactiveX/RxSwift/blob/master/RxExample/RxExample/Services/GeolocationService.swift
struct City {
let name: String
}
struct CityService{
私有init(){}
静态let shared=CityService()
lazy var nearbyCities:驱动程序={
返回GeolocationService.instance.location
.flatMapLatest({坐标在
let location=CLLocation(纬度:坐标。纬度,经度:坐标。经度)
return CityService.shared.fetchNearbyCitiesFor(位置)
}).asDriver(onErrorJustReturn:[])
}()
func fetchNearbyCitiesFor(u位置:CLLocation)->可观察{
返回可观察的。在中创建{observer
让一次性的=一次性的。创建()
//模拟从网络获取:
let cities=[城市(名称:“阿姆斯特丹”)、城市(名称:“柏林”)]
onNext观察员(城市)
观察员。在(.completed)
一次性退货
}
}
}
类别地理定位服务{
静态let实例=GeolocationService()
专用(设置)变量位置:驱动程序
}
//发件人:https://github.com/ReactiveX/RxSwift/blob/master/RxExample/RxExample/Services/GeolocationService.swift
结构城市{
let name:String
}
但是,由于以下原因,这不是编译:
Cannot convert value of type 'SharedSequence<DriverSharingStrategy, [Any]>' to specified type 'Driver<[City]>'
(aka 'SharedSequence<DriverSharingStrategy, Array<City>>')
无法将“SharedSequence”类型的值转换为指定的“Driver”类型
(又名“共享序列”)
我还尝试添加一些类型提示以获得更好的错误:
lazy var nearbyCities: Driver<[City]> = {
return GeolocationService.shared.location
.flatMapLatest({ coordinate -> Observable<[City]> in
let location = CLLocation(latitude: coordinate.latitude, longitude: coordinate.longitude)
let nearbyCities: Observable<[City]> = CityService.shared.fetchNearbyCitiesFor(location)
return nearbyCities.catch
}).asDriver(onErrorJustReturn: [City]())
}()
lazy-var-nearbyCities:Driver={
返回GeolocationService.shared.location
.flatMapLatest({坐标->在
let location=CLLocation(纬度:坐标。纬度,经度:坐标。经度)
let nearbyCities:Observable=CityService.shared.fetchNearbyCitiesFor(位置)
返回附近城市
}).asDriver(onErrorJustReturn:[City]())
}()
但这给了我的是:
Cannot convert value of type '(_) -> Observable<[City]>' to expected argument type '(CLLocationCoordinate2D) -> SharedSequence<_, _>'
无法将类型为“()->Observable”的值转换为预期的参数类型“(CLLocationCoordinate2D)->SharedSequence”
我做错了什么?你把
.asDriver
调用放错地方了
lazy var nearbyCities: Driver<[City]> = {
return GeolocationService.instance.location
.flatMapLatest({ (coordinate) -> Driver<[City]> in
let location = CLLocation(latitude: coordinate.latitude, longitude: coordinate.longitude)
return CityService.shared.fetchNearbyCitiesFor(location)
.asDriver(onErrorJustReturn: [])
})
}()
lazy-var-nearbyCities:Driver={
返回GeolocationService.instance.location
.flatMapLatest({(坐标)->中的驱动程序
let location=CLLocation(纬度:坐标。纬度,经度:坐标。经度)
return CityService.shared.fetchNearbyCitiesFor(位置)
.asDriver(onErrorJustReturn:[])
})
}()
啊!是的,终于。谢谢。不过,我还是不能对司机掉以轻心。。有没有最新RxSwift的好资源?