Class PdfAttachmentCollection

Manages the collection of file attachments embedded in a PDF document. Supports adding, removing, and iterating through attachments.

Access this collection via Attachments property.

Example - Manage attachments:

var pdf = PdfDocument.FromFile("document.pdf");

// Add attachment:
byte[] excelData = File.ReadAllBytes("report.xlsx");
pdf.Attachments.AddAttachment("Q4_Report.xlsx", excelData);


// List all attachments:
foreach (var att in pdf.Attachments)
Console.WriteLine($"{att.Index}: {att.Name}");


// Remove first attachment:
pdf.Attachments.RemoveAttachment(pdf.Attachments[0]);


pdf.SaveAs("modified.pdf");

Inheritance
System.Object
PdfClientAccessor
PdfAttachmentCollection
Implements
System.Collections.Generic.IEnumerable<PdfAttachment>
System.Collections.IEnumerable
Namespace: IronPdf
Assembly: IronPdf.dll
Syntax
public class PdfAttachmentCollection : PdfClientAccessor

PDF generation in IronPDF is handled through PdfAttachmentCollection. It manages the collection of file attachments embedded in a PDF document.

PdfAttachmentCollection matters when an application needs to configure or invoke PDF generation from C# code. The class encapsulates the related options and behavior in a single object that is set up once and reused across render or processing calls. Typical scenarios include batch generation pipelines, templated document workflows, and integration with existing C# document services.

To use PdfAttachmentCollection, instantiate or obtain it from the relevant entry point in the IronPDF C# API. Key properties include Item[Int32]. Assign options or invoke methods on the instance to configure or perform the operation. The add remove attachments covers typical usage in C# end to end.

using IronPdf;

// Obtain PdfAttachmentCollection from the relevant entry point in the IronPDF API
void Configure(PdfAttachmentCollection instance)
{
    var current = instance.Item[Int32];
    instance.AddAttachment();
}

For the broader workflow, see the access PDF DOM object guide in the IronPDF C# documentation. For broader context, the PDF generation portion of the IronPDF C# API contains related types that work with PdfAttachmentCollection directly. PdfAttachmentCollection instances inherit additional members from PdfClientAccessor that may be relevant in advanced scenarios. In application code, treat PdfAttachmentCollection as a configured object that is constructed once and reused across operations rather than instantiated per call. Configuration is generally idempotent: assigning the same property value twice has the same effect as assigning it once. For diagnostic purposes, inspect the relevant PdfAttachmentCollection property after each operation to confirm the configured state. See the constructors, properties, and methods tables below for the complete API surface of PdfAttachmentCollection. Application code typically obtains or instantiates a single PdfAttachmentCollection and shares it across multiple IronPDF operations rather than recreating it per call.

Properties

Item[Int32]

Gets the attachment at the specified index within this collection.

Example:

var firstAttachment = pdf.Attachments[0];
File.WriteAllBytes(firstAttachment.Name, firstAttachment.Data);

Declaration
public PdfAttachment this[int index] { get; }
Parameters
Type Name Description
System.Int32 index

Zero-based index of the attachment to retrieve.
Property Value
Type Description
PdfAttachment

The PdfAttachment at the specified index.
Exceptions
Type Condition
System.ArgumentOutOfRangeException

Index is outside the valid range.

Methods

AddAttachment(String, Byte[])

Embeds a file as an attachment within the PDF document. The attachment appears as a paperclip icon in PDF readers and can be extracted by users.

Example - Attach supporting files:

// Attach Excel report:
byte[] excelData = File.ReadAllBytes("financials.xlsx");
pdf.Attachments.AddAttachment("Q4_Financials.xlsx", excelData);

// Attach multiple files:
foreach (var file in Directory.GetFiles("receipts"))
{
var data = File.ReadAllBytes(file);
pdf.Attachments.AddAttachment(Path.GetFileName(file), data);
}

Declaration
public PdfAttachment AddAttachment(string name, byte[] data)
Parameters
Type Name Description
System.String name

Filename for the attachment including extension (e.g., "report.xlsx", "receipt.pdf"). This name will appear in PDF readers.
System.Byte[] data

Complete binary content of the file to attach. Use File.ReadAllBytes() to read from disk.
Returns
Type Description
PdfAttachment

The newly created PdfAttachment for further manipulation.
Remarks

Attachments increase PDF file size by the size of attached files.

For PDF/A-3 compliant attachments (e.g., ZUGFeRD invoices), see with EmbedFileConfiguration.

Standards:

See Also

GetEnumerator()

Retrieve enumerator

Declaration
public IEnumerator<PdfAttachment> GetEnumerator()
Returns
Type Description
System.Collections.Generic.IEnumerator<PdfAttachment>

Enumerator

RemoveAttachment(PdfAttachment)

Removes the specified attachment from the PDF document permanently.

Example - Remove sensitive attachments:

// Remove specific attachment by reference:
var pdf = PdfDocument.FromFile("document.pdf");
var sensitiveFile = pdf.Attachments.FirstOrDefault(
    a => a.Name.Contains("confidential"));
if (sensitiveFile != null)
    pdf.Attachments.RemoveAttachment(sensitiveFile);

// Remove all attachments:
while (pdf.Attachments.Any())
pdf.Attachments.RemoveAttachment(pdf.Attachments[0]);


pdf.SaveAs("cleaned.pdf");

Declaration
public void RemoveAttachment(PdfAttachment attachment)
Parameters
Type Name Description
PdfAttachment attachment

The PdfAttachment instance to remove. Obtain from indexer or enumeration.
Remarks

After removal, indexes of remaining attachments may change due to automatic alphabetical sorting.

See Also

Implements

System.Collections.Generic.IEnumerable<>
System.Collections.IEnumerable

See Also