Create, read, and edit Excel files in UWP

21 Jul 202024 minutes to read

Syncfusion Excel library for UWP platform can be used to create, read, edit Excel files. This also convert Excel files to PDF.

Create a simple Excel report

The below steps illustrates creating an simple Invoice formatted Excel document in UWP application.

1.Create a new C# Blank App (Universal Windows) project.

Create UWP application in Visual Studio

2.Install the Syncfusion.XlsIO.UWP NuGet package as reference to your .NET Framework applications from NuGet.org.

Add XlsIO reference to the project

3.Add a new button in the MainPage.xaml as shown below.

<Page
    x:Class="GettingStarted_UWP.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:GettingStarted_UWP"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <Grid>
        <Button x:Name="button" Content="Create Document" Click="OnButtonClicked" HorizontalAlignment="Center" VerticalAlignment="Center"/>
    </Grid>
</Page>

4.Include the following namespaces in the MainPage.xaml.cs file.

using Syncfusion.XlsIO;
using Windows.Storage.Pickers;
using Windows.Storage;
using Windows.UI;
Imports Syncfusion.XlsIO
Imports Windows.Storage.Pickers
Imports Windows.Storage
Imports Windows.UI

5.Include the below code snippet in the click event of the button in MainPage.xaml.cs, to create an Excel file and save the Excel document as a physical file and open the file for viewing.

//Create an instance of ExcelEngine.
using (ExcelEngine excelEngine = new ExcelEngine())
{
	IApplication application = excelEngine.Excel;

	application.DefaultVersion = ExcelVersion.Excel2016;

	//Create a workbook with a worksheet
	IWorkbook workbook = application.Workbooks.Create(1);

	//Access first worksheet from the workbook instance.
	IWorksheet worksheet = workbook.Worksheets[0];

	Assembly executingAssembly = typeof(MainPage).GetTypeInfo().Assembly;
	Stream inputStream = executingAssembly.GetManifestResourceStream("GettingStarted_UWP.AdventureCycles-Logo.png");

	//Add a picture
	IPictureShape shape = worksheet.Pictures.AddPicture(1, 1, inputStream);

	//Disable gridlines in the worksheet
	worksheet.IsGridLinesVisible = false;

	//Enter values to the cells from A3 to A5
	worksheet.Range["A3"].Text = "46036 Michigan Ave";
	worksheet.Range["A4"].Text = "Canton, USA";
	worksheet.Range["A5"].Text = "Phone: +1 231-231-2310";

	//Make the text bold
	worksheet.Range["A3:A5"].CellStyle.Font.Bold = true;

	//Merge cells
	worksheet.Range["D1:E1"].Merge();

	//Enter text to the cell D1 and apply formatting.
	worksheet.Range["D1"].Text = "INVOICE";
	worksheet.Range["D1"].CellStyle.Font.Bold = true;
	worksheet.Range["D1"].CellStyle.Font.RGBColor = ColorHelper.FromArgb(0, 42, 118, 189);
	worksheet.Range["D1"].CellStyle.Font.Size = 35;

	//Apply alignment in the cell D1
	worksheet.Range["D1"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignRight;
	worksheet.Range["D1"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;

	//Enter values to the cells from D5 to E8
	worksheet.Range["D5"].Text = "INVOICE#";
	worksheet.Range["E5"].Text = "DATE";
	worksheet.Range["D6"].Number = 1028;
	worksheet.Range["E6"].Value = "12/31/2018";
	worksheet.Range["D7"].Text = "CUSTOMER ID";
	worksheet.Range["E7"].Text = "TERMS";
	worksheet.Range["D8"].Number = 564;
	worksheet.Range["E8"].Text = "Due Upon Receipt";

	//Apply RGB backcolor to the cells from D5 to E8
	worksheet.Range["D5:E5"].CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189);
	worksheet.Range["D7:E7"].CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189);

	//Apply known colors to the text in cells D5 to E8
	worksheet.Range["D5:E5"].CellStyle.Font.Color = ExcelKnownColors.White;
	worksheet.Range["D7:E7"].CellStyle.Font.Color = ExcelKnownColors.White;

	//Make the text as bold from D5 to E8
	worksheet.Range["D5:E8"].CellStyle.Font.Bold = true;

	//Apply alignment to the cells from D5 to E8
	worksheet.Range["D5:E8"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
	worksheet.Range["D5:E5"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
	worksheet.Range["D7:E7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
	worksheet.Range["D6:E6"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;

	//Enter value and applying formatting in the cell A7
	worksheet.Range["A7"].Text = "  BILL TO";
	worksheet.Range["A7"].CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189);
	worksheet.Range["A7"].CellStyle.Font.Bold = true;
	worksheet.Range["A7"].CellStyle.Font.Color = ExcelKnownColors.White;

	//Apply alignment
	worksheet.Range["A7"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
	worksheet.Range["A7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;

	//Enter values in the cells A8 to A12
	worksheet.Range["A8"].Text = "Steyn";
	worksheet.Range["A9"].Text = "Great Lakes Food Market";
	worksheet.Range["A10"].Text = "20 Whitehall Rd";
	worksheet.Range["A11"].Text = "North Muskegon,USA";
	worksheet.Range["A12"].Text = "+1 231-654-0000";

	//Create a Hyperlink for e-mail in the cell A13
	IHyperLink hyperlink = worksheet.HyperLinks.Add(worksheet.Range["A13"]);
	hyperlink.Type = ExcelHyperLinkType.Url;
	hyperlink.Address = "Steyn@greatlakes.com";
	hyperlink.ScreenTip = "Send Mail";

	//Enter details of products and prices
	worksheet.Range["A15"].Text = "  DESCRIPTION";
	worksheet.Range["C15"].Text = "QTY";
	worksheet.Range["D15"].Text = "UNIT PRICE";
	worksheet.Range["E15"].Text = "AMOUNT";
	worksheet.Range["A16"].Text = "Cabrales Cheese";
	worksheet.Range["A17"].Text = "Chocos";
	worksheet.Range["A18"].Text = "Pasta";
	worksheet.Range["A19"].Text = "Cereals";
	worksheet.Range["A20"].Text = "Ice Cream";
	worksheet.Range["C16"].Number = 3;
	worksheet.Range["C17"].Number = 2;
	worksheet.Range["C18"].Number = 1;
	worksheet.Range["C19"].Number = 4;
	worksheet.Range["C20"].Number = 3;
	worksheet.Range["D16"].Number = 21;
	worksheet.Range["D17"].Number = 54;
	worksheet.Range["D18"].Number = 10;
	worksheet.Range["D19"].Number = 20;
	worksheet.Range["D20"].Number = 30;
	worksheet.Range["D23"].Text = "Total";

	//Apply number format
	worksheet.Range["D16:E22"].NumberFormat = "$.00";
	worksheet.Range["E23"].NumberFormat = "$.00";

	//Merge column A and B from row 15 to 22
	worksheet.Range["A15:B15"].Merge();
	worksheet.Range["A16:B16"].Merge();
	worksheet.Range["A17:B17"].Merge();
	worksheet.Range["A18:B18"].Merge();
	worksheet.Range["A19:B19"].Merge();
	worksheet.Range["A20:B20"].Merge();
	worksheet.Range["A21:B21"].Merge();
	worksheet.Range["A22:B22"].Merge();

	//Apply incremental formula for column Amount by multiplying Qty and UnitPrice
	application.EnableIncrementalFormula = true;
	worksheet.Range["E16:E20"].Formula = "=C16*D16";

	//Formula for Sum the total
	worksheet.Range["E23"].Formula = "=SUM(E16:E22)";

	//Apply borders
	worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
	worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
	worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Grey_25_percent;
	worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Grey_25_percent;
	worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
	worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
	worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Black;
	worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Black;

	//Apply font setting for cells with product details
	worksheet.Range["A3:E23"].CellStyle.Font.FontName = "Arial";
	worksheet.Range["A3:E23"].CellStyle.Font.Size = 10;
	worksheet.Range["A15:E15"].CellStyle.Font.Color = ExcelKnownColors.White;
	worksheet.Range["A15:E15"].CellStyle.Font.Bold = true;
	worksheet.Range["D23:E23"].CellStyle.Font.Bold = true;

	//Apply cell color
	worksheet.Range["A15:E15"].CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189);

	//Apply alignment to cells with product details
	worksheet.Range["A15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
	worksheet.Range["C15:C22"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
	worksheet.Range["D15:E15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;

	//Apply row height and column width to look good
	worksheet.Range["A1"].ColumnWidth = 36;
	worksheet.Range["B1"].ColumnWidth = 11;
	worksheet.Range["C1"].ColumnWidth = 8;
	worksheet.Range["D1:E1"].ColumnWidth = 18;
	worksheet.Range["A1"].RowHeight = 47;
	worksheet.Range["A2"].RowHeight = 15;
	worksheet.Range["A3:A4"].RowHeight = 15;
	worksheet.Range["A5"].RowHeight = 18;
	worksheet.Range["A6"].RowHeight = 29;
	worksheet.Range["A7"].RowHeight = 18;
	worksheet.Range["A8"].RowHeight = 15;
	worksheet.Range["A9:A14"].RowHeight = 15;
	worksheet.Range["A15:A23"].RowHeight = 18;


	// Save the Workbook
	StorageFile storageFile;
	if (!(Windows.Foundation.Metadata.ApiInformation.IsTypePresent("Windows.Phone.UI.Input.HardwareButtons")))
	{
		FileSavePicker savePicker = new FileSavePicker();
		savePicker.SuggestedStartLocation = PickerLocationId.Desktop;
		savePicker.SuggestedFileName = "Output";
		savePicker.FileTypeChoices.Add("Excel Files", new List<string>() { ".xlsx" });
		storageFile = await savePicker.PickSaveFileAsync();
	}
	else
	{
		StorageFolder local = Windows.Storage.ApplicationData.Current.LocalFolder;
		storageFile = await local.CreateFileAsync("Output.xlsx", CreationCollisionOption.ReplaceExisting);
	}
	//Saving the workbook
	await workbook.SaveAsAsync(storageFile);

	// Launch the saved file
	await Windows.System.Launcher.LaunchFileAsync(storageFile);
}
Private Sub OnButtonClicked(ByVal sender As Object, ByVal args As EventArgs)
'Create an instance of ExcelEngine
Using excelEngine As ExcelEngine = New ExcelEngine()

	Dim application As IApplication = excelEngine.Excel

	application.DefaultVersion = ExcelVersion.Excel2016

	'Create a workbook
	Dim workbook As IWorkbook = application.Workbooks.Create(1)
	Dim worksheet As IWorksheet = workbook.Worksheets(0)

	'Adding a picture
	Dim executingAssembly As Assembly = GetType(MainPage).GetTypeInfo().Assembly
	Dim inputStream As Stream = executingAssembly.GetManifestResourceStream("GettingStarted_UWP.AdventureCycles-Logo.png")
	Dim shape As IPictureShape = worksheet.Pictures.AddPicture(1, 1, inputStream)

	'Disable gridlines in the worksheet
	worksheet.IsGridLinesVisible = False

	'Enter values to the cells from A3 to A5
	worksheet.Range("A3").Text = "46036 Michigan Ave"
	worksheet.Range("A4").Text = "Canton, USA"
	worksheet.Range("A5").Text = "Phone: +1 231-231-2310"

	'Make the text bold
	worksheet.Range("A3:A5").CellStyle.Font.Bold = True

	'Merge cells
	worksheet.Range("D1:E1").Merge()

	'Enter text to the cell D1 and apply formatting.
	worksheet.Range("D1").Text = "INVOICE"
	worksheet.Range("D1").CellStyle.Font.Bold = True
	worksheet.Range("D1").CellStyle.Font.RGBColor = ColorHelper.FromArgb(0, 42, 118, 189)
	worksheet.Range("D1").CellStyle.Font.Size = 35

	'Apply alignment in the cell D1
	worksheet.Range("D1").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignRight
	worksheet.Range("D1").CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop

	'Enter values to the cells from D5 to E8
	worksheet.Range("D5").Text = "INVOICE#"
	worksheet.Range("E5").Text = "DATE"
	worksheet.Range("D6").Number = 1028
	worksheet.Range("E6").Value = "12/31/2018"
	worksheet.Range("D7").Text = "CUSTOMER ID"
	worksheet.Range("E7").Text = "TERMS"
	worksheet.Range("D8").Number = 564
	worksheet.Range("E8").Text = "Due Upon Receipt"

	'Apply RGB back color to the cells from D5 to E8
	worksheet.Range("D5:E5").CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189)
	worksheet.Range("D7:E7").CellStyle.Color = ColorHelper.FromArgb(0,42, 118, 189)

	'Apply known colors to the text in cells D5 to E8
	worksheet.Range("D5:E5").CellStyle.Font.Color = ExcelKnownColors.White
	worksheet.Range("D7:E7").CellStyle.Font.Color = ExcelKnownColors.White

	'Make the text as bold from D5 to E8
	worksheet.Range("D5:E8").CellStyle.Font.Bold = True

	'Apply alignment to the cells from D5 to E8
	worksheet.Range("D5:E8").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter
	worksheet.Range("D5:E5").CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter
	worksheet.Range("D7:E7").CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter
	worksheet.Range("D6:E6").CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop

	'Enter value and applying formatting in the cell A7
	worksheet.Range("A7").Text = "  BILL TO"
	worksheet.Range("A7").CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189)
	worksheet.Range("A7").CellStyle.Font.Bold = True
	worksheet.Range("A7").CellStyle.Font.Color = ExcelKnownColors.White

	'Apply alignment
	worksheet.Range("A7").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft
	worksheet.Range("A7").CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter

	'Enter values in the cells A8 to A12
	worksheet.Range("A8").Text = "Steyn"
	worksheet.Range("A9").Text = "Great Lakes Food Market"
	worksheet.Range("A10").Text = "20 Whitehall Rd"
	worksheet.Range("A11").Text = "North Muskegon,USA"
	worksheet.Range("A12").Text = "+1 231-654-0000"

	'Create a Hyperlink for e-mail in the cell A13
	Dim hyperlink As IHyperLink = worksheet.HyperLinks.Add(worksheet.Range("A13"))
	hyperlink.Type = ExcelHyperLinkType.Url
	hyperlink.Address = "Steyn@greatlakes.com"
	hyperlink.ScreenTip = "Send Mail"

	'Merge column A and B from row 15 to 22
	worksheet.Range("A15:B15").Merge()
	worksheet.Range("A16:B16").Merge()
	worksheet.Range("A17:B17").Merge()
	worksheet.Range("A18:B18").Merge()
	worksheet.Range("A19:B19").Merge()
	worksheet.Range("A20:B20").Merge()
	worksheet.Range("A21:B21").Merge()
	worksheet.Range("A22:B22").Merge()

	'Enter details of products and prices
	worksheet.Range("A15").Text = "  DESCRIPTION"
	worksheet.Range("C15").Text = "QTY"
	worksheet.Range("D15").Text = "UNIT PRICE"
	worksheet.Range("E15").Text = "AMOUNT"
	worksheet.Range("A16").Text = "Cabrales Cheese"
	worksheet.Range("A17").Text = "Chocos"
	worksheet.Range("A18").Text = "Pasta"
	worksheet.Range("A19").Text = "Cereals"
	worksheet.Range("A20").Text = "Ice Cream"
	worksheet.Range("C16").Number = 3
	worksheet.Range("C17").Number = 2
	worksheet.Range("C18").Number = 1
	worksheet.Range("C19").Number = 4
	worksheet.Range("C20").Number = 3
	worksheet.Range("D16").Number = 21
	worksheet.Range("D17").Number = 54
	worksheet.Range("D18").Number = 10
	worksheet.Range("D19").Number = 20
	worksheet.Range("D20").Number = 30
	worksheet.Range("D23").Text = "Total"

	'Apply number format
	worksheet.Range("D16:E22").NumberFormat = "$.00"
	worksheet.Range("E23").NumberFormat = "$.00"

	'Apply incremental formula for column Amount by multiplying Qty and UnitPrice
	application.EnableIncrementalFormula = True
	worksheet.Range("E16:E20").Formula = "=C16*D16"

	'Formula for Sum the total
	worksheet.Range("E23").Formula = "=SUM(E16:E22)"

	'Apply borders
	worksheet.Range("A16:E22").CellStyle.Borders(ExcelBordersIndex.EdgeTop).LineStyle = ExcelLineStyle.Thin
	worksheet.Range("A16:E22").CellStyle.Borders(ExcelBordersIndex.EdgeBottom).LineStyle = ExcelLineStyle.Thin
	worksheet.Range("A16:E22").CellStyle.Borders(ExcelBordersIndex.EdgeTop).Color = ExcelKnownColors.Grey_25_percent
	worksheet.Range("A16:E22").CellStyle.Borders(ExcelBordersIndex.EdgeBottom).Color = ExcelKnownColors.Grey_25_percent
	worksheet.Range("A23:E23").CellStyle.Borders(ExcelBordersIndex.EdgeTop).LineStyle = ExcelLineStyle.Thin
	worksheet.Range("A23:E23").CellStyle.Borders(ExcelBordersIndex.EdgeBottom).LineStyle = ExcelLineStyle.Thin
	worksheet.Range("A23:E23").CellStyle.Borders(ExcelBordersIndex.EdgeTop).Color = ExcelKnownColors.Black
	worksheet.Range("A23:E23").CellStyle.Borders(ExcelBordersIndex.EdgeBottom).Color = ExcelKnownColors.Black

	'Apply font setting for cells with product details
	worksheet.Range("A3:E23").CellStyle.Font.FontName = "Arial"
	worksheet.Range("A3:E23").CellStyle.Font.Size = 10
	worksheet.Range("A15:E15").CellStyle.Font.Color = ExcelKnownColors.White
	worksheet.Range("A15:E15").CellStyle.Font.Bold = True
	worksheet.Range("D23:E23").CellStyle.Font.Bold = True

	'Apply cell color
	worksheet.Range("A15:E15").CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189)

	'Apply alignment to cells with product details
	worksheet.Range("A15").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft
	worksheet.Range("C15:C22").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter
	worksheet.Range("D15:E15").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter

	'Apply row height and column width to look good
	worksheet.Range("A1").ColumnWidth = 36
	worksheet.Range("B1").ColumnWidth = 11
	worksheet.Range("C1").ColumnWidth = 8
	worksheet.Range("D1:E1").ColumnWidth = 18
	worksheet.Range("A1").RowHeight = 47
	worksheet.Range("A2").RowHeight = 15
	worksheet.Range("A3:A4").RowHeight = 15
	worksheet.Range("A5").RowHeight = 18
	worksheet.Range("A6").RowHeight = 29
	worksheet.Range("A7").RowHeight = 18
	worksheet.Range("A8").RowHeight = 15
	worksheet.Range("A9:A14").RowHeight = 15
	worksheet.Range("A15:A23").RowHeight = 18

	'Save the Workbook
	Dim storageFile As StorageFile
	If Not Windows.Foundation.Metadata.ApiInformation.IsTypePresent("Windows.Phone.UI.Input.HardwareButtons") Then
		Dim savePicker As FileSavePicker = New FileSavePicker
		savePicker.SuggestedStartLocation = PickerLocationId.Desktop
		savePicker.SuggestedFileName = "Output"
		savePicker.FileTypeChoices.Add("Excel Files", New List(Of String))
		storageFile = savePicker.PickSaveFileAsync
	Else
		Dim local As StorageFolder = Windows.Storage.ApplicationData.Current.LocalFolder
		storageFile = local.CreateFileAsync("Output.xlsx", CreationCollisionOption.ReplaceExisting)
	End If

	'Saving the workbook
	Function workbook_SaveAsAsync_((ByVal Unknown As storageFile) As await Implements workbook.SaveAsAsync.(Of
	End Function

	'Launch the saved file
	Function Windows_System_Launcher_LaunchFileAsync_((ByVal Unknown As storageFile) As await Implements Windows.System.Launcher.LaunchFileAsync.(Of
	End Function
End Using

A complete working example of how to create an Excel file in UWP can be downloaded from Create-Excel-file.zip.

By executing the program, you will get the Excel file as below.
Output File

Read and Edit Excel file

The below code illustrates how to read and edit an Excel file in UWP.

//Create an instance of ExcelEngine
ExcelEngine excelEngine = new ExcelEngine();

IApplication application = excelEngine.Excel;

//Instantiates the File Picker. 
FileOpenPicker openPicker = new FileOpenPicker();
openPicker.SuggestedStartLocation = PickerLocationId.Desktop;
openPicker.FileTypeFilter.Add(".xlsx");
openPicker.FileTypeFilter.Add(".xls");
StorageFile openFile = await openPicker.PickSingleFileAsync();

//Opens the workbook. 
IWorkbook workbook = await application.Workbooks.OpenAsync(openFile);

//Access first worksheet from the workbook.
IWorksheet worksheet = workbook.Worksheets[0];

//Set Text in cell A3.
worksheet.Range["A3"].Text ="Hello World";

//Sets workbook version.
workbook.Version = ExcelVersion.Excel2013;

//Initializes FileSavePicker.
FileSavePicker savePicker = new FileSavePicker();
savePicker.SuggestedStartLocation = PickerLocationId.Desktop;
savePicker.SuggestedFileName = "CreateSpreadsheet";
savePicker.FileTypeChoices.Add("Excel Files", new List<string>() { ".xlsx" });

//Creates a storage file from FileSavePicker.
StorageFile storageFile = await savePicker.PickSaveFileAsync();

//Saves changes to the specified storage file.
await workbook.SaveAsAsync(storageFile);

workbook.Close();
excelEngine.Dispose();
'Create an instance of ExcelEngine
Dim excelEngine As ExcelEngine = New ExcelEngine()

Dim application As IApplication = excelEngine.Excel

'Instantiates the File Save Picker.  
Dim openPicker As New FileOpenPicker()
openPicker.SuggestedStartLocation = PickerLocationId.Desktop 
openPicker.FileTypeFilter.Add(".xlsx") 
openPicker.FileTypeFilter.Add(".xls") 
Dim openFile As StorageFile = Await openPicker.PickSingleFileAsync()

'Opens the Workbook. 
Dim workbook As IWorkbook = Await application.Workbooks.OpenAsync(openFile)
Dim workbook.SaveAsAsyncCType(As await, openFile)

'Access first worksheet from the workbook.
Dim worksheet As IWorksheet = workbook.Worksheets(0)

'Set Text in cell A3.
worksheet.Range("A3").Text ="Hello World"

'Sets workbook version.
workbook.Version = ExcelVersion.Excel2013

'Initializes FileSavePicker.
Dim savePicker As New FileSavePicker()
savePicker.SuggestedStartLocation = PickerLocationId.Desktop
savePicker.SuggestedFileName = "CreateSpreadsheet"
savePicker.FileTypeChoices.Add("Excel Files", New List(Of String)() From {".xlsx"})

'Creates a storage file from FileSavePicker.
Dim storageFile As StorageFile = Await savePicker.PickSaveFileAsync()

'Saves changes to the specified storage file.
Await workbook.SaveAsAsync(storageFile)

workbook.Close()
excelEngine.Dispose()

NOTE

Starting with v16.2.0.x, if you reference Syncfusion assemblies from trial setup or from the NuGet feed, you also have to add “Syncfusion.Licensing” assembly reference and include a license key in your projects. Please refer to this link to know about registering Syncfusion license key in your applications to use our components.