--- title: "iOS PDF annotation library: Draw, circle, markup | Nutrient" canonical_url: "https://www.nutrient.io/guides/ios/annotations/introduction-to-annotations/" md_url: "https://www.nutrient.io/guides/ios/annotations/introduction-to-annotations.md" last_updated: "2026-05-14T16:53:43.860Z" description: "Master PDF annotation on iOS with Nutrient SDK. Create, edit, and remove annotations using a robust API or intuitive UI for 17 annotation types." --- # PDF annotation library for iOS Nutrient iOS SDK is a library for creating, removing, and editing PDF annotations. It offers developers a robust API for programmatic annotation management, as well as a beautiful UI for working with 17 PDF annotation types. ## What are annotations? Content displayed as a PDF page isn’t suitable for easy editing, but the PDF specification defines a comprehensive set of objects that can be added to PDF pages without changing the page content. These objects are called annotations, and their purpose ranges from marking up page content to implementing interactive features such as forms. [Learn more](https://www.nutrient.io/guides/ios/annotations/introduction-to-annotations/what-are-annotations.md) ## Essential guides --- **Supported annotation types** Learn about the types of annotations supported by Nutrient [Read more](https://www.nutrient.io/guides/ios/annotations/introduction-to-annotations/annotation-types.md) --- **Annotation data formats** Learn about using external files to manage annotations [Read more](https://www.nutrient.io/guides/ios/annotations/introduction-to-annotations/data-formats.md) --- **Annotation replies and reviews** Learn about annotation replies and reviews [Read more](https://www.nutrient.io/guides/ios/annotations/replies.md) --- **Flatten annotations** How to flatten annotations and burn them into a PDF [Read more](https://www.nutrient.io/guides/ios/annotations/flatten.md) --- **Freeform annotation rotation** Learn about annotation rotation and how to configure it [Read more](https://www.nutrient.io/guides/ios/annotations/annotation-rotation.md) --- **Magic Ink** How to add and configure the Magic Ink tool [Read more](https://www.nutrient.io/guides/ios/annotations/magic-ink.md) ## Synchronization --- **Synchronization overview** Learn about the different approaches to annotation syncing [Read more](https://www.nutrient.io/guides/ios/annotations/synchronization.md) --- **Storing annotation data** Learn best practices for storing annotation data [Read more](https://www.nutrient.io/guides/ios/annotations/synchronization/storing-annotation-data.md) --- **Concurrent user conflict resolution** Learn best practices for conflict resolution with concurrent users [Read more](https://www.nutrient.io/guides/ios/annotations/synchronization/conflict-resolution.md) ## Saving and storing annotations --- **Saving annotations overview** Learn the two ways Nutrient allows making changes to documents [Read more](https://www.nutrient.io/guides/ios/annotations/annotation-saving-mechanism.md) --- **Embed annotations into a PDF** How to embed annotations into a PDF document [Read more](https://www.nutrient.io/guides/ios/annotations/save/embed-into-pdf.md) --- **Save annotations to external storage** How to save annotations to external storage [Read more](https://www.nutrient.io/guides/ios/importing-exporting/annotation-providers.md) --- **Auto save annotations** How to configure the way changes are automatically saved [Read more](https://www.nutrient.io/guides/ios/annotations/annotation-and-bookmark-saving-triggers.md) ## Import and export --- **To/from Document Engine** How to import/export annotations to/from the optional Document Engine [Read more](https://www.nutrient.io/guides/ios/annotations/import-and-export/document-engine.md) --- **To/from Instant JSON** How to import/export annotations to/from Instant JSON [Read more](https://www.nutrient.io/guides/ios/importing-exporting/instant-json.md) --- **To/from XFDF** How to import/export annotations to/from XFDF [Read more](https://www.nutrient.io/guides/ios/importing-exporting/xfdf-support.md) --- **To/from a database** How to import/export annotations to/from a database [Read more](https://www.nutrient.io/guides/ios/annotations/import-and-export/database.md) ## Create, edit, remove --- **Programmatic creation, editing, or removal** How to programmatically create, edit, or remove annotations [Read more](https://www.nutrient.io/guides/ios/annotations/programmatically-creating-annotations.md) --- **Stamp configuration** How to create a custom stamp [Read more](https://www.nutrient.io/guides/ios/annotations/image-annotations.md) --- **Link annotations** How to create, detect, and customize link annotations [Read more](https://www.nutrient.io/guides/ios/annotations/link-annotations.md) --- **Undo and redo** Learn about the undo and redo functionality for annotations [Read more](https://www.nutrient.io/guides/ios/features/undo-redo.md) --- **Annotate on an image** How to annotate a PNG, JPG, or TIFF [Read more](https://www.nutrient.io/guides/ios/annotations/annotate-images.md) --- **Video annotations** How to embed video into a PDF [Read more](https://www.nutrient.io/guides/ios/annotations/video-annotations.md) --- **Detect changes to annotations** How to detect annotation changes that originate from the UI [Read more](https://www.nutrient.io/guides/ios/annotations/detecting-if-annotations-have-changed.md) --- **Annotation flags** How to configure annotation behavior and capabilities [Read more](https://www.nutrient.io/guides/ios/annotations/annotation-flags.md) --- **Image picker** How to configure the image picker for adding an image annotation [Read more](https://www.nutrient.io/guides/ios/miscellaneous/image-picker.md) --- **Annotation author name** How to configure the author name for annotations [Read more](https://www.nutrient.io/guides/ios/annotations/annotation-author-name.md) --- **Attach a file** How to programmatically create a file annotation with an embedded file [Read more](https://www.nutrient.io/guides/ios/annotations/create-edit-and-remove/attach-a-file.md) --- **Disable annotation editing** How to disable the modification of individual annotations or types [Read more](https://www.nutrient.io/guides/ios/annotations/create-edit-and-remove/disable-editing.md) --- **Create annotations via drag and drop** Learn about dragging and dropping elements onto a page [Read more](https://www.nutrient.io/guides/ios/annotations/create-edit-and-remove/drag-and-drop.md) --- **Annotation blend modes** How to set blend modes for annotations [Read more](https://www.nutrient.io/guides/ios/annotations/annotation-blend-modes.md) --- **Annotation z-index** How to change the z-index of an annotation [Read more](https://www.nutrient.io/guides/ios/annotations/annotation-z-index.md) ## Customization --- **Customize appearance streams** How to render existing appearance streams [Read more](https://www.nutrient.io/guides/ios/annotations/appearance-streams.md) --- **Hiding annotations** How to hide individual annotations or annotation types [Read more](https://www.nutrient.io/guides/ios/annotations/disable-rendered-annotation-types.md) --- **Customize default properties** How to configure the default value for annotation properties [Read more](https://www.nutrient.io/guides/ios/annotations/changing-default-values-for-color-and-text-size-of-annotations.md) --- **Customize annotation color presets** How to customize the default color presets in the style inspector [Read more](https://www.nutrient.io/guides/ios/annotations/customizing-presets.md) --- **Customize the note icon** How to customize or hide the note icon [Read more](https://www.nutrient.io/guides/ios/annotations/customize-annotation-rendering.md) --- **Fixed annotation size** How to create an annotation that has a fixed size and doesn’t scale [Read more](https://www.nutrient.io/guides/ios/annotations/fixed-size-annotations.md) --- **Store custom data in an annotation** How to store and process custom data inside an annotation [Read more](https://www.nutrient.io/guides/ios/annotations/custom-data-in-annotations.md) ## More annotation guides --- **Annotation object model** How to use the `Annotation` and `FormElement` classes [Read more](https://www.nutrient.io/guides/ios/annotations/the-annotation-object-model.md) --- **Stamp a document with built-in stamps** How to stamp a document programmatically or with the UI [Read more](https://www.nutrient.io/guides/ios/annotations/stamp-annotations-configuration.md) --- **Multimedia annotations** How to display multimedia/gallery annotations [Read more](https://www.nutrient.io/guides/ios/annotations/multimedia-annotations.md) --- **Image document specification** Learn how PNGs, JPGs, and TIFFs are annotated by Nutrient [Read more](https://www.nutrient.io/guides/ios/features/image-document-standard.md) --- **Annotation state manager** How to programmatically set the states used for annotation creation [Read more](https://www.nutrient.io/guides/ios/annotations/annotation-state-manager.md) --- **PDF actions support** Learn about the PDF actions supported by Nutrient [Read more](https://www.nutrient.io/guides/ios/annotations/pdf-actions.md) ## Apple Pencil --- **Apple Pencil customization** How to customize how Apple Pencil interacts with Nutrient [Read more](https://www.nutrient.io/guides/ios/annotations/apple-pencil.md) --- **Double tap** Learn about built-in support for Apple Pencil double-taps [Read more](https://www.nutrient.io/guides/ios/annotations/apple-pencil-double-tap-actions.md) **Call to Action** Start your free trial for unlimited access and expert support. [Learn More](https://www.nutrient.io/sdk/ios/getting-started.md) --- ## Related pages - [Flatten annotations on iOS](/guides/ios/annotations/flatten.md) - [How to rotate annotations on iOS](/guides/ios/annotations/annotation-rotation.md) - [Magic Ink tool: Draw and detect annotation shapes](/guides/ios/annotations/magic-ink.md) - [Review and reply to annotations on iOS](/guides/ios/annotations/replies.md) ## Pages in this section - [Supported PDF annotation types on iOS](/guides/ios/annotations/introduction-to-annotations/annotation-types.md) - [What are PDF annotations?](/guides/ios/annotations/introduction-to-annotations/what-are-annotations.md) - [Compare XFDF and Instant JSON for PDF annotations](/guides/ios/annotations/introduction-to-annotations/data-formats.md)