---
title: "PDF form object model on iOS | Nutrient SDK"
canonical_url: "https://www.nutrient.io/guides/ios/forms/create-edit-and-remove/form-object-model/"
md_url: "https://www.nutrient.io/guides/ios/forms/create-edit-and-remove/form-object-model.md"
last_updated: "2026-05-15T17:18:57.897Z"
description: "Under the hood, PDF form elements are a type of PDF annotation called widget annotations. They’re used to implement interactive form elements."
---

# Form object model on iOS

Under the hood, PDF form elements are a type of PDF annotation called widget annotations. They’re used to implement interactive form elements, such as buttons, checkboxes, combo boxes, and more.

As such, the form object model is identical to the annotation object model. See our [annotation object model](https://www.nutrient.io/guides/ios/annotations/the-annotation-object-model.md) guide to learn more.
---

## Related pages

- [How to disable PDF form editing on iOS devices](/guides/ios/forms/create-edit-and-remove/disable-editing.md)
- [Creating fillable PDF forms on iOS](/guides/ios/forms/form-creation.md)
- [PDF form field editor on iOS](/guides/ios/forms/create-edit-and-remove/edit-fields.md)
- [PDF form field flags on iOS](/guides/ios/forms/create-edit-and-remove/form-field-flags.md)
- [Programmatically add signature fields to PDF forms](/guides/ios/forms/create-edit-and-remove/add-signature-field.md)