Lấy chữ ký từ PDF trong .NET SDK

using Aspose.Pdf.Cloud.Sdk.Model;

namespace Signatures
{
    public class GetSignatures
    {
        public static async Task Extract(string documentName, string remoteFolder)
        {
		// Get your AppSid and AppSecret from https://dashboard.aspose.cloud (free registration required). 
		pdfApi = new PdfApi(AppSecret, AppSid);

                using (var file = File.OpenRead(Path.Combine(localFolder, documentName)))
		{ // Upload the local PDF to cloud storage folder name.
                    FilesUploadResult uploadResponse = await pdfApi.UploadFileAsync(Path.Combine(remoteFolder, documentName), documentName);
                    Console.WriteLine(uploadResponse.Uploaded[0]);
                }

                // Get signatures from the PDF in cloud storage.
                SignatureFieldsResponse response = await pdfApi.GetDocumentSignatureFieldsAsync(documentName, folder: remoteFolder);

                // Checks the response and logs the result.
                if (response == null)
                    Console.WriteLine("GetSignatures(): Unexpected error!");
                else if (response.Code < 200 || response.Code > 299)
                    Console.WriteLine("GetSignatures(): Failed to receive signatures from the document.");
                else if (response.Fields == null ||  response.Fields.List == null ||  response.Fields.List.Count == 0)
                    Console.WriteLine("GetSignatures(): signatures not found in the document.");
                else
                { // Show signatures.
                    Console.WriteLine("GetSignatures(): Signatures extracted successfully from the Pdf document '{0}'.", documentName);
                    foreach (var field in response.Fields.List) {
                        Console.WriteLine(field);
                    }
                }
            }
        }
    }