How do you use IFormFieldCollection in C# code?

Accept IFormFieldCollection as a parameter or return type in C# code that needs to work uniformly across IronPDF implementors. The interface defines the contract; concrete behavior is provided by the implementor returned at runtime.

What is the difference between IFormFieldCollection and a concrete implementor?

IFormFieldCollection is the interface contract; its concrete implementors carry the actual behavior. Reference IFormFieldCollection when writing code that should work across multiple implementors; use a concrete type when a single implementor's behavior is required.

Which namespace and assembly contain IFormFieldCollection?

IFormFieldCollection is in the IronSoftware.Forms namespace, shipped in IronPdf.dll. It extends IList . Concrete classes such as FormFieldCollection implement it.

Interface IFormFieldCollection

Q: What implements IFormFieldCollection in IronPDF?

Concrete implementors of IFormFieldCollection in IronPDF include FormFieldCollection. Code that accepts IFormFieldCollection works uniformly across all implementors, with a cast to the concrete type only required when type-specific behavior is needed.

Form field collection list

Namespace: IronSoftware.Forms

Assembly: IronPdf.dll

Syntax

public interface IFormFieldCollection

IFormFieldCollection is what IronPDF hands back when C# code reads PDF forms. It represents form field collection list, so code can work with PDF forms uniformly across implementors rather than binding to a concrete type.

Concrete implementors include FormFieldCollection, IronPDF concrete implementor. Code that accepts IFormFieldCollection works uniformly across these implementors, so applications can read or configure C# PDF features without binding to a specific concrete type.

Most of the usable surface is inherited. The members that carry everyday use of this contract are DisableFormFontFallback, FindFormField, SetFormFont; consult these first when implementing or consuming IFormFieldCollection.

using IronPdf;

// IFormFieldCollection is consumed as the API surface for the family of implementors
void Consume(IFormFieldCollection target)
{
    // Use members defined on the interface; concrete behavior follows the implementor
}

For collection-wide operations and end-to-end examples, see the IronPDF C# documentation for related guides. For collection-wide operations on IFormFieldCollection instances, the IronPDF C# documentation lists the relevant container types and their methods. Concrete behavior depends on which implementor of IFormFieldCollection is returned at runtime; consult the specific class reference for type-specific members. Polymorphic access through IFormFieldCollection lets code work uniformly across the family of implementors, with a cast required only when type-specific behavior is needed. The reference tables below list the full set of members defined on IFormFieldCollection along with any inherited members exposed through the contract. In a typical IronPDF C# workflow, IFormFieldCollection appears as a parameter or return type at the boundary between the application and the IronPDF API. See the methods table below for the complete set of members defined directly on IFormFieldCollection. Implementing IFormFieldCollection directly in application code is uncommon; the typical pattern is to consume instances returned from the IronPDF API. When iterating over a collection of IFormFieldCollection instances, prefer the inherited members for portable code; downcast only when type-specific behavior is required.

Methods

DisableFormFontFallback()

Suppresses the automatic font fallback embed for non-ASCII form values.

Declaration

void DisableFormFontFallback()

FindFormField(String)

Find a form field with the specified name. First tries to match a fully-qualified name. If a fully-qualified match cannot be found, then partial name matches are tried.

Declaration

IFormField FindFormField(string Name)

Parameters

Type	Name	Description
System.String	Name	Form field name

Returns

Type	Description
IFormField	Form field with the specified name

SetFormFont(String, Byte[], Boolean)

Sets the document-wide font for subsequent form-field fills.

Declaration

void SetFormFont(string fontName, byte[] fontData, bool forceEmbed = false)

Parameters

Type	Name	Description
System.String	fontName
System.Byte[]	fontData
System.Boolean	forceEmbed