如何在触发计时器发布程序时调用URLSession发布程序
如何在触发计时器发布程序时调用URLSession发布程序
提问于 2021-06-14 20:31:12
我想每隔60分钟调用一个基于计时器发布器的URLSession发布器。
看起来这应该是可能的，但不知道该怎么做：
例如：
struct Response: Codable {
// ... some fields here
}
class MyClass: ObservableObject {
@Published var response: Response? = nil
var cancelable : AnyCancelable?
func connectPoller() {
let timer = Timer.TimerPublisher(interval: 60 * 60, runLoop: .main, mode: .default)
// how to chain this?
// want to connect the timer to invoke the data task
URLSession.shared.dataTaskPublisher(for: URL(string: "some-url-here")!).tryMap() { element -> Data in
guard let httpResponse = element.response as? HTTPURLResponse,
httpResponse.statusCode == 200 else {
throw URLError(.badServerResponse)
}
return element.data
}.decode(type: Response?.self, decoder: JSONDecoder()).eraseToAnyPublisher()
.replaceError(with: nil).assign(to: \.response, on: self)
}
}回答 2
Stack Overflow用户
发布于 2021-06-14 23:33:51
class MyClass: ObservableObject {
@Published var response: Response? = nil
var cancelable : AnyCancellable?
func connectPoller() {
let timer = Timer.TimerPublisher(interval: 60 * 60, runLoop: .main, mode: .default)
.autoconnect() //<= here
cancelable = timer
.flatMap { _ in
URLSession.shared.dataTaskPublisher(for: URL(string: "some-url-here")!).tryMap() { element -> Data in
guard let httpResponse = element.response as? HTTPURLResponse,
httpResponse.statusCode == 200 else {
throw URLError(.badServerResponse)
}
return element.data
}
.decode(type: Response?.self, decoder: JSONDecoder()).eraseToAnyPublisher()
.replaceError(with: nil)
}
.receive(on: RunLoop.main) //<= here
.assign(to: \.response, on: self)
}
}Stack Overflow用户
发布于 2021-06-14 23:37:18
为了将Timer发布程序转换为URLSession dataTask发布程序，您需要使用flatMap。此外，您需要确保发布器链不能完成，因为计时器将在该点停止触发。因此，您需要对flatMap内部的错误进行更积极的清理，以便它们不会进一步向下传播。
class MyClass: ObservableObject {
@Published var response: Response? = nil
var cancellable : AnyCancellable?
func connectPoller() {
cancellable = Timer.publish(every: 5, on: .main, in: .default)
.autoconnect()
.flatMap { _ in
URLSession.shared.dataTaskPublisher(for: URL(string: "https://google.com")!)
.flatMap { element -> AnyPublisher<Data,Never> in
guard let httpResponse = element.response as? HTTPURLResponse,
httpResponse.statusCode == 200 else {
return Just(Data()).eraseToAnyPublisher()
}
return Just(element.data).eraseToAnyPublisher()
}
.decode(type: Response?.self, decoder: JSONDecoder())
.replaceError(with: nil)
}
.print()
.receive(on: RunLoop.main)
.assign(to: \.response, on: self)
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/67970269
复制相关文章
相似问题
腾讯云开发者
