I need to wrap a function as below from a library into an async function. The error on my First Trial as below is:
Missing argument for parameter 'errorHandler' in call.
How can I wrap it properly? Your comments will be appreciated.
Original Function:
func createConverter(id: String, successHandler: @escaping (Converter) -> Void, errorHandler: @escaping (Error) -> Void) -> Cancellable
func createConverter(id: String) async throws -> Converter {
return await withCheckedThrowingContinuation({
(continuation: CheckedContinuation<Converter, Error>) in
createConverter(id: id) { result in
switch result {
case .success(let converter):
continuation.resume(returning: converter)
case .failure(let error):
continuation.resume(throwing: error)
}
}
})
}
Since the original createConverter
has three parameters, you need to provide all three. You are missing the 3rd. Your attempt assumes there is only one closure parameter (of type Result<Converter, Error>
) instead of the two separate closure parameters.
You should also add try
before the await
.
func createConverter(id: String) async throws -> Converter {
return try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Converter, Error>) in
let cancellable = createConverter(id: id) { (converter: Converter) in
continuation.resume(returning: converter)
} errorHandler: { error in
continuation.resume(throwing: error)
}
}
}
This compiles but I have no way to verify the result. This also makes no use of the original Cancellable
return value of the original createConverter
.
Since I don't have whatever library you have, this was verified in a Playground using the following:
import Combine
// Dummy
struct Converter {
}
// Original function
func createConverter(id: String, successHandler: @escaping (Converter) -> Void, errorHandler: @escaping (Error) -> Void) -> Cancellable {
return AnyCancellable { // Just enough so it compiles
}
}
// New function
func createConverter(id: String) async throws -> Converter {
return try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Converter, Error>) in
let cancellable = createConverter(id: id) { (converter: Converter) in
continuation.resume(returning: converter)
} errorHandler: { error in
continuation.resume(throwing: error)
}
}
}