Is it possible to not declare function as async and still run an async operation in it which will re-CodePudding

I'm currently re-writing a lot of code to use new async/await mechanism, but I want to do it piece by piece instead of changing every file in my project to use async/await.

How would I go about converting method that used completion handler, like this:

func fetchLibrary(completion: ((Error?) -> Void)?) {
    apiManager.loadLibraryContent { [weak self] result in
        switch result {
        case .success(let records):
            let databaseError = self?.databaseManager.updateDatabase(withNewRecords: records)
            completion?(databaseError)
        case .failure(let error):
            completion?(error)
        }
    }
}

Then update the loadLibraryContent method of apiManager to look like this:

func loadLibraryContent() async throws -> [GRDBRecord] {

And still be able use the completion handler in the first method? It would make gradual migration to async/await easier.

Ideally the new code would look something like this:

func fetchLibrary(completion: ((Error?) -> Void)?) {
    do {
        let records = try await apiManager.loadLibraryContent()
        let databaseError = self?.databaseManager.updateDatabase(withNewRecords: records)
        completion?(databaseError)
    } catch {
        completion?(error)
    }
}

Is it possible to do in Swift?

CodePudding user response：

You can use Task

    func fetchLibrary(completion: ((Error?) -> Void)?) {
        Task {
            do {
                let records = try await apiManager.loadLibraryContent()
                let databaseError = self?.databaseManager.updateDatabase(withNewRecords: records)
                completion?(databaseError)
            } catch {
                completion?(error)
            }
        }
    }