APIRequest-PostExtension.Swift

extension APIRequest {
    public static func post<R: Codable & APIEndpoint, T: Codable, E: Codable>(
        request: R,
        onSuccess: @escaping ((_: T) -> Void),
        onError: @escaping ((_: E?, _: Error) -> Void)) {

        guard var endpointRequest = self.urlRequest(from: request) else {
            onError(nil, APIError.invalidEndpoint)
            return
        }
        endpointRequest.httpMethod = "POST"
        endpointRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")

        do {
            endpointRequest.httpBody = try JSONEncoder().encode(request)
        } catch {
            onError(nil, error)
            return
        }

        URLSession.shared.dataTask(
            with: endpointRequest,
            completionHandler: { (data, urlResponse, error) in
                DispatchQueue.main.async {
                    self.processResponse(data, urlResponse, error, onSuccess: onSuccess, onError: onError)
                }
        }).resume()
    }
}