将带有completionHandler 的函数转换为Combine

Question

我试图将我的函数从使用完成处理程序更改为使用组合的函数，但我收到一条错误消息。

1. 使用完成处理程序：

    typealias AuthorizationCompletion = (UNAuthorizationStatus) -> ()
   
    func reloadAuthorizationStatus(completion: @escaping AuthorizationCompletion) {
    UNUserNotificationCenter.current().getNotificationSettings { settings in
        DispatchQueue.main.async {
            let notificationStatus = settings.authorizationStatus
            completion(notificationStatus)
        }
    }
   

2. 使用组合：

    func reloadAuthorizationStatus() -> AnyPublisher<UNAuthorizationStatus, Error>  {
    UNUserNotificationCenter.current().getNotificationSettings { settings in
        Just(settings)
            .tryMap({$0.authorizationStatus})
            .eraseToAnyPublisher()
    }
   

但出现错误无法将类型“Void”的返回表达式转换为返回类型“AnyPublisher<UNAuthorizationStatus, Error>”

从我将返回类型添加到函数的那一刻起，设置 let 将从 UNNotificationSettings 类型更改为错误类型

我在这里缺少什么？

Answer 1

Future是您需要的发布商

func reloadAuthorizationStatus() -> AnyPublisher<UNAuthorizationStatus, Never>  {
    Future<UNAuthorizationStatus, Never> { promise in
        UNUserNotificationCenter.current()
            .getNotificationSettings { settings in
            promise(.success(settings.authorizationStatus))
        }
    }
    .eraseToAnyPublisher()
}