Wrapping Asynchronous Functions In ReactiveSwift

reactiveSwiftWrapper.swift

// Mock External Library Definitions
func mockAsyncFunction(completion: @escaping (String?, MockError?) -> Void ) {
	DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
		completion("mockAsyncFunction completed successfully", nil)
//		uncomment the below line and comment the one above to return an error
//		completion(nil, MockError.asyncError)
	}
}

enum MockError: Error, LocalizedError {
	case asyncError
	var errorDescription: String? {
		switch self {
		case .asyncError:
			return "Async had an error"
		}
	}
}

// Simple Use of Asynchronous Library Function
mockAsyncFunction { (optionalReturnedString, optionalReturnedError) in
	if let returnedString = optionalReturnedString {
		print(returnedString)
	} else if let returnedError = optionalReturnedError {
		print(returnedError)
	}
}

// Wrapping Asynchronous Function
func wrappedFunction() -> SignalProducer<String, MockError> {
	return SignalProducer { observer, disposable in
		mockAsyncFunction { (optionalReturnedString, optionalReturnedError) in
			if let returnedString = optionalReturnedString {
				observer.send(value: returnedString)
				observer.sendCompleted()
			} else if let returnedError = optionalReturnedError {
				observer.send(error: returnedError)
			}
		}
	}
}

// Simple Use of Asynchronous ReactiveSwift Function
wrappedFunction().startWithResult { result in
	if let returnedString = result.value {
		print(returnedString)
	} else if let returnedError = result.error {
		print(returnedError)
	}
}