PdfDocument doc = new PdfDocument(inputFile);
            if (doc.DocumentPieceInfo==null) {
                doc.DocumentPieceInfo = new PdfPieceInfo();
            }
            doc.DocumentPieceInfo.AddApplicationData("ice","this is a uu");
            doc.DocumentPieceInfo.AddApplicationData("blie", "this is a uu");
            doc.DocumentPieceInfo.AddApplicationData("blue", "this is a uu");
            doc.DocumentPieceInfo.AddApplicationData("jis", "this is a uu");
            doc.DocumentPieceInfo.RemoveApplicationData("blie");

            if (doc.Pages[0].PagePieceInfo==null) {
                doc.Pages[0].PagePieceInfo = new PdfPieceInfo();
            }

            doc.Pages[0].PagePieceInfo.AddApplicationData("ice", "this is a uu");
            doc.Pages[0].PagePieceInfo.AddApplicationData("blie", "this is a 2222uu");
            doc.Pages[0].PagePieceInfo.AddApplicationData("blue", "this is a 3333uu");
            doc.Pages[0].PagePieceInfo.AddApplicationData("jis", "this is a 4444uu");
            doc.Pages[0].PagePieceInfo.RemoveApplicationData("blie");

            StringBuilder sb = new StringBuilder();
            IDictionary<sstring, PdfApplicationData> dic = doc.Pages[0].PagePieceInfo.ApplicationDatas;
            foreach (string item in dic.Keys) {
                PdfApplicationData data = dic[item];
                if (data.Private is String) {

                    string ss = data.Private as string;
                    sb.AppendLine(ss);
                }
            }
            File.WriteAllText(outputFile_txt, sb.ToString());
            doc.SaveToFile(outputFile);

string input = @"Field.pdf";
PdfDocument doc = new PdfDocument();
doc.LoadFromFile(input);
PdfFormWidget formWidget = doc.Form as PdfFormWidget;
if (formWidget != null)
{
//method 1
//formWidget.FieldsWidget.Clear();
for (int i = formWidget.FieldsWidget.List.Count - 1; i >= 0; i--)
{ 
//method2 
PdfField field = formWidget.FieldsWidget.List[i] as PdfField; formWidget.FieldsWidget.Remove(field);
}
}
string output = "DeleteFormField.pdf";
doc.SaveToFile(output);

PdfDocument doc = new PdfDocument();
MemoryStream stream = new MemoryStream(File.ReadAllBytes("test.pdf"));
doc.Collection.AddFile("file.pdf", stream);
doc.SaveToFile("result.pdf");

var pivotTable = sheet.PivotTables[0];
((Spire.Xls.PivotTable)pivotTable).ChangeDataSource(sheet.Range["A1:C9"]);

wb.Worksheets[0].Pictures[0].ChangeLayer(ShapeLayerChangeType.BringForward);
wb.Worksheets[1].Pictures[0].ChangeLayer(ShapeLayerChangeType.BringToFront);
wb.Worksheets[2].Pictures[1].ChangeLayer(ShapeLayerChangeType.SendBackward);
wb.Worksheets[3].Pictures[1].ChangeLayer(ShapeLayerChangeType.SendToBack); 

//copy the theme from Excel
workbook.CopyTheme(srcWorkbook);
//set theme color 
workbook.SetThemeColor(ThemeColorType.Accent1, Color.Blue);
//get theme color
Color color = workbook.GetThemeColor(ThemeColorType.Accent2);
//set style as theme color
style.SetThemeColor(ThemeColorType.Lt1, 0.1);
//get theme color of style
bool isThemeColor = style.GetThemeColor(out themeType, out tint);

sheet.GetFreezePanes(out rowIndex, out colIndex);