Alamofire Request Error Handling - From their documentation

Alamofire.request.error.handling.swift

Alamofire.request(urlString).responseJSON { response in
    guard case let .failure(error) = response.result else { return }

    if let error = error as? AFError {
        switch error {
        case .invalidURL(let url):
            print("Invalid URL: \(url) - \(error.localizedDescription)")
        case .parameterEncodingFailed(let reason):
            print("Parameter encoding failed: \(error.localizedDescription)")
            print("Failure Reason: \(reason)")
        case .multipartEncodingFailed(let reason):
            print("Multipart encoding failed: \(error.localizedDescription)")
            print("Failure Reason: \(reason)")
        case .responseValidationFailed(let reason):
            print("Response validation failed: \(error.localizedDescription)")
            print("Failure Reason: \(reason)")

            switch reason {
            case .dataFileNil, .dataFileReadFailed:
                print("Downloaded file could not be read")
            case .missingContentType(let acceptableContentTypes):
                print("Content Type Missing: \(acceptableContentTypes)")
            case .unacceptableContentType(let acceptableContentTypes, let responseContentType):
                print("Response content type: \(responseContentType) was unacceptable: \(acceptableContentTypes)")
            case .unacceptableStatusCode(let code):
                print("Response status code was unacceptable: \(code)")
            }
        case .responseSerializationFailed(let reason):
            print("Response serialization failed: \(error.localizedDescription)")
            print("Failure Reason: \(reason)")
        }

        print("Underlying error: \(error.underlyingError)")
    } else if let error = error as? URLError {
        print("URLError occurred: \(error)")
    } else {
        print("Unknown error: \(error)")
    }
}