How to edit PDFs in an iOS application using a PDF library

Jonathan D. Rhyne

Updated: June 3, 2026

How to edit PDFs in an iOS application using a PDF library

TL;DR

Nutrient iOS SDK lets you edit PDFs programmatically and through a built-in UI:

Use the Processor class to rotate, crop, move, remove, and add pages, as well as to apply permanent watermarks.
Switch the PDFViewController to content editing mode to edit text directly.
Attach embedded files to a page with a FileAnnotation.

In this post, you’ll learn how to edit PDFs using Nutrient iOS SDK. More specifically, you’ll learn how to perform the following editing operations on a PDF document in your iOS application:

iOS ships with Apple’s PDFKit for displaying PDFs, but editing them — rearranging pages, editing text, adding signatures or watermarks — goes beyond what the native framework covers. This post uses Nutrient’s iOS PDF library for those operations; the comparison near the end covers when PDFKit is enough and when a dedicated library earns its place.

Requirements

To get started, you’ll need:

A computer running macOS
The latest stable version of Xcode(opens in a new tab)

Getting started

To follow along, create a fresh Xcode project and add the Nutrient Swift package to your project. For step-by-step instructions, follow our Getting Started on iOS guide.

Rotating PDF pages using the Processor class

The Processor class provides APIs for document editing operations. Many Processor operations involve producing an output that’s the result of performing editing operations on an input document.

Use Processor when you want to build an automated document processing operation.

Load the document you want to edit:

let fileURL = Bundle.main.url(forResource: "YOUR-DOCUMENT", withExtension: "pdf")!
let document = Document(url: fileURL)

Configure the page rotation parameters on a Processor.Configuration instance:

 guard let configuration = Processor.Configuration(document: document) else {
        print("Could not create a processor configuration. The document might be locked or invalid.")
        return
    }

configuration.rotatePage(0, by: 90)

Construct a URL to write the modified document:

let editedDocumentURl = URL(filePath: NSTemporaryDirectory() + "/document-rotated.pdf")

Apply the configuration and write the edited document:

let processor = Processor(configuration: configuration, securityOptions: nil)
do {
    try processor.write(toFileURL: editedDocumentURl)
} catch {
    print(error)
}

Load the edited document and present the PDF view controller:

let editedDocument = Document(url: editedDocumentURl)

let pdfController = PDFViewController(document: editedDocument)

present(UINavigationController(rootViewController: pdfController), animated: true)

For a working example, replace the contents of ViewController.swift with the following:

import UIKit
import PSPDFKit
import PSPDFKitUI

class ViewController: UIViewController {

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        let fileURL = Bundle.main.url(forResource: "YOUR-DOCUMENT", withExtension: "pdf")!
        let document = Document(url: fileURL)

        guard let configuration = Processor.Configuration(document: document) else {
            print("Could not create a processor configuration. The document might be locked or invalid.")
            return
        }

        // Rotate the first page 90 degrees clockwise.
        configuration.rotatePage(0, by: 90)

        let editedDocumentURL = URL(filePath: NSTemporaryDirectory() + "/document-rotated.pdf")

        let processor = Processor(configuration: configuration, securityOptions: nil)
        do {
            // Write the modified document. `editedDocumentURL` can be used
            // to initialize and present the edited document.
            try processor.write(toFileURL: editedDocumentURL)
        } catch {
            print(error)
        }

        let editedDocument = Document(url: editedDocumentURL)

        let pdfController = PDFViewController(document: editedDocument)

        // Present the PDF view controller within a `UINavigationController` to show built-in toolbar buttons.
        present(UINavigationController(rootViewController: pdfController), animated: true)

    }
}

Remember to replace YOUR-DOCUMENT with the document you want to edit.

Rotating the first page of a PDF 90 degrees in the iOS Simulator

Cropping PDF pages using the Processor class

To crop a page of your document using Processor, configure the page cropping parameters on a Processor.Configuration instance:

// Crop the page to 200×200 pt.
configuration.changeCropBoxForPage(at: 0, to: CGRect(x: 0, y: 0, width: 200, height: 200))

For a working example, replace the contents of ViewController.swift with the following:

import UIKit
import PSPDFKit
import PSPDFKitUI

class ViewController: UIViewController {

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        let fileURL = Bundle.main.url(forResource: "YOUR-DOCUMENT", withExtension: "pdf")!
        let document = Document(url: fileURL)

        guard let configuration = Processor.Configuration(document: document) else {
            print("Could not create a processor configuration. The document might be locked or invalid.")
            return
        }

        // Crop the page to 200×200 pt.
        configuration.changeCropBoxForPage(at: 0, to: CGRect(x: 0, y: 0, width: 200, height: 200))

        let editedDocumentURL = URL(filePath: NSTemporaryDirectory() + "/document-cropped.pdf")

        let processor = Processor(configuration: configuration, securityOptions: nil)
        do {
            // Write the modified document. `editedDocumentURL` can be used
            // to initialize and present the edited document.
            try processor.write(toFileURL: editedDocumentURL)
        } catch {
            print(error)
        }

        let editedDocument = Document(url: editedDocumentURL)

        // The configuration closure is optional and allows additional customization.
        let pdfController = PDFViewController(document: editedDocument)

        // Present the PDF view controller within a `UINavigationController` to show built-in toolbar buttons.
        present(UINavigationController(rootViewController: pdfController), animated: true)

    }
}

Make sure that the file path used in editedDocumentURL is unique in the containing directory so that existing documents aren’t overwritten.

Cropping a PDF page to a 200×200 pt box in the iOS Simulator

Moving PDF pages using the Processor class

To move pages via the Processor API, configure the page move parameters on a Processor.Configuration instance:

// Move the first page to the end of the document.
configuration.movePages(IndexSet(integer: 0), toDestinationIndex: document.pageCount)

Moving the first PDF page to the end of the document in the iOS Simulator

Removing pages using the Processor class

To remove pages via the Processor API, configure the page removal parameters on a Processor.Configuration instance:

// Remove the first page. This API can be used to remove multiple pages at the same time.
configuration.removePages(IndexSet(integer: 0))

Removing the first page from a PDF in the iOS Simulator

Adding new pages using the Processor class

For this example, you’ll add a blank page to your document using the Processor API. You can add a blank page to a document using the .blank template document.

Create a blank page template:

let pageTemplate = PageTemplate(pageType: .emptyPage, identifier: .blank)

Create a new page configuration:

let newPageConfiguration = PDFNewPageConfiguration(pageTemplate: pageTemplate, builderBlock: nil)

Configure the add new page parameters:

configuration.addNewPage(at: 1, configuration: newPageConfiguration)

You’ll have the following in your ViewController.swift:

import UIKit
import PSPDFKit
import PSPDFKitUI

class ViewController: UIViewController {

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        let fileURL = Bundle.main.url(forResource: "YOUR-DOCUMENT", withExtension: "pdf")!
        let document = Document(url: fileURL)

        guard let configuration = Processor.Configuration(document: document) else {
            print("Could not create a processor configuration. The document might be locked or invalid.")
            return
        }

        // Create a blank page template.
        let pageTemplate = PageTemplate(pageType: .emptyPage, identifier: .blank)
        // Create a new page configuration.
        let newPageConfiguration = PDFNewPageConfiguration(pageTemplate: pageTemplate, builderBlock: nil)
        // Add the blank page at index 1.
        configuration.addNewPage(at: 1, configuration: newPageConfiguration)

        let editedDocumentURl = URL(filePath: NSTemporaryDirectory() + "/document-new-page.pdf")

        let processor = Processor(configuration: configuration, securityOptions: nil)
        do {
            // Write the modified document. `editedDocumentURL` can be used
            // to initialize and present the edited document.
            try processor.write(toFileURL: editedDocumentURl)
        } catch {
            print(error)
        }

        let editedDocument = Document(url: editedDocumentURl)

        // The configuration closure is optional and allows additional customization.
        let pdfController = PDFViewController(document: editedDocument)

        // Present the PDF view controller within a `UINavigationController` to show built-in toolbar buttons.
        present(UINavigationController(rootViewController: pdfController), animated: true)

    }
}

Adding a blank page at index 1 of a PDF in the iOS Simulator

Editing text in PDFs

Nutrient enables you to edit text directly in PDF documents using the built-in user interface via Content Editor. You can change the text color, the font type, and the font size, and you can move and resize text boxes. Content Editor is a separately licensed component — reach out to add it to your license.

To enable content editing programmatically after loading a document, set the view mode to .contentEditing:

let controller = PDFViewController(document: document)
controller.setViewMode(.contentEditing, animated: true)

For a working example, replace the contents of ViewController.swift with the following:

import UIKit
import PSPDFKit
import PSPDFKitUI

class ViewController: UIViewController {

    override func viewDidAppear(_ animated: Bool) {
       super.viewDidAppear(animated)

       // Update to use your document name.
       let fileURL = Bundle.main.url(forResource: "YOUR-DOCUMENT", withExtension: "pdf")!
       let document = Document(url: fileURL)

       let controller = PDFViewController(document: document)
       controller.setViewMode(.contentEditing, animated: true)
       present(UINavigationController(rootViewController: controller), animated: true)

   }
}

Editing PDF text in content-editing mode in the iOS Simulator

Attaching files to PDFs

You can programmatically attach embedded files to a FileAnnotation object. You can create a file annotation with an embedded file using the URL of any file.

A working example looks like this:

import UIKit
import PSPDFKit
import PSPDFKitUI

class ViewController: UIViewController {

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        // Update to use your document name.
        let fileURL = Bundle.main.url(forResource: "YOUR-DOCUMENT", withExtension: "pdf")!
        let document = Document(url: fileURL)

        // Create a new file annotation and set its properties.
        let fileAnnotation = FileAnnotation()
        fileAnnotation.pageIndex = 0
        fileAnnotation.iconName = .graph
        fileAnnotation.color = .blue
        fileAnnotation.boundingBox = CGRect(x: 500, y: 250, width: 32, height: 32)

        let embeddedFileURL = Bundle.main.url(forResource: "DOCUMENT-TO-EMBED", withExtension: "pdf")!
        let embeddedFile = EmbeddedFile(fileURL: embeddedFileURL, fileDescription: "Sample Document")
        fileAnnotation.embeddedFile = embeddedFile

        document.add(annotations: [fileAnnotation])

        // The configuration closure is optional and allows additional customization.
        let pdfController = PDFViewController(document: document)

        // Present the PDF view controller within a `UINavigationController` to show built-in toolbar buttons.
        present(UINavigationController(rootViewController: pdfController), animated: true)

    }
}

Attaching an embedded file to a PDF page with a file annotation in the iOS Simulator

Adding watermarks to PDFs using the Processor class

Nutrient enables you to draw a permanent watermark on all pages of a document using the Processor API. The resulting PDF file will have a permanent watermark on all of its pages, even when opened in other PDF editors:

configuration.drawOnAllCurrentPages { context, pageIndex, pageRect, renderOptions in
    // Careful. This code is executed on background threads. Only use thread-safe drawing methods.
    let text = "Nutrient Live Watermark On Page \(pageIndex + 1)"
    let stringDrawingContext = NSStringDrawingContext()
    stringDrawingContext.minimumScaleFactor = 0.1

    // Add text over the diagonal of the page.
    context.translateBy(x: 0, y: pageRect.size.height / 2)
    context.rotate(by: -.pi / 4)
    let attributes: [NSAttributedString.Key: Any] = [
        .font: UIFont.boldSystemFont(ofSize: 30),
        .foregroundColor: UIColor.red.withAlphaComponent(0.5)
    ]
    text.draw(with: pageRect, options: .usesLineFragmentOrigin, attributes: attributes, context: stringDrawingContext)
}

For a working example, replace the contents of ViewController.swift with the following:

import UIKit
import PSPDFKit
import PSPDFKitUI

class ViewController: UIViewController {

    override func viewDidAppear(_ animated: Bool) {
       super.viewDidAppear(animated)

       // Update to use your document name.
       let fileURL = Bundle.main.url(forResource: "document-ios", withExtension: "pdf")!
       let document = Document(url: fileURL)

       guard let configuration = Processor.Configuration(document: document) else {
           print("Could not create a processor configuration. The document might be locked or invalid.")
           return
       }

       configuration.drawOnAllCurrentPages { context, pageIndex, pageRect, renderOptions in
           // Careful. This code is executed on background threads. Only use thread-safe drawing methods.
           let text = "Nutrient Live Watermark On Page \(pageIndex + 1)"
           let stringDrawingContext = NSStringDrawingContext()
           stringDrawingContext.minimumScaleFactor = 0.1

           // Add text over the diagonal of the page.
           context.translateBy(x: 0, y: pageRect.size.height / 2)
           context.rotate(by: -.pi / 4)
           let attributes: [NSAttributedString.Key: Any] = [
               .font: UIFont.boldSystemFont(ofSize: 30),
               .foregroundColor: UIColor.red.withAlphaComponent(0.5)
           ]
           text.draw(with: pageRect, options: .usesLineFragmentOrigin, attributes: attributes, context: stringDrawingContext)
       }

        let editedDocumentURl = URL(filePath: NSTemporaryDirectory() + "/document-watermark.pdf")

       let processor = Processor(configuration: configuration, securityOptions: nil)
       do {
           // Write the modified document. `editedDocumentURL` can be used
           // to initialize and present the edited document.
           try processor.write(toFileURL: editedDocumentURl)
       } catch {
           print(error)
       }

       let editedDocument = Document(url: editedDocumentURl)

       // The configuration closure is optional and allows additional customization.
       let pdfController = PDFViewController(document: editedDocument)

       // Present the PDF view controller within a `UINavigationController` to show built-in toolbar buttons.
       present(UINavigationController(rootViewController: pdfController), animated: true)

   }

}

Drawing a permanent diagonal watermark on every PDF page in the iOS Simulator

Apple PDFKit vs. Nutrient

iOS includes Apple’s PDFKit, a system framework that’s easy to integrate and a solid starting point for displaying PDFs. It provides a viewer (PDFView), thumbnails, text selection and extraction, the document outline, and basic annotations.

Where a dedicated library earns its place is the editing and document work beyond viewing. Compared to PDFKit, Nutrient iOS SDK adds:

A configurable UI that supports most PDF features
Every annotation type in the PDF specification, with import and export in JSON and XFDF
Programmatic form filling
Electronic and digital signatures
Page editing — add, remove, duplicate, rotate, and extract pages
Permanent watermarks and access to embedded files
Indexed full-text search with near-instant results
First-class support from our engineers

If you only need to display PDFs and add the occasional basic annotation, PDFKit may be enough. If your app needs to edit, annotate, fill, sign, or search documents, that’s where Nutrient fits. To move an existing PDFKit integration over, the migrating from Apple PDFKit guide maps the APIs across.

Conclusion

In this post, you learned how to edit a PDF document using Nutrient’s iOS PDF editor library. If you hit any snags while trying to implement any of the steps, reach out to our Support team for help. If you want to learn more about how you can use Nutrient’s iOS library in your projects, you can reach out to our team.