--- title: "iOS PDF signature library — Fast and easy setup | Nutrient" canonical_url: "https://www.nutrient.io/guides/ios/signatures/" md_url: "https://www.nutrient.io/guides/ios/signatures.md" last_updated: "2026-06-03T21:45:02.511Z" description: "Master the art of adding electronic signatures on iOS with our comprehensive guide. Unlock valuable secrets to improve your workflow." --- # iOS PDF signature library Nutrient iOS SDK is a library for signing PDF documents with an electronic signature or with encrypted certificate-based digital signatures. It offers developers an API to create, validate, and display digitally signed documents, as well as a beautiful UI for hand-drawn electronic signatures. ## Introduction to signatures Nutrient facilitates paperless signing workflows with the [Electronic Signatures](https://www.nutrient.io/sdk/solutions/signing/) and [Digital Signatures](https://www.nutrient.io/sdk/solutions/signing/) components. These are two components that can be licensed separately and don’t depend on each other. [Learn more](https://www.nutrient.io/guides/ios/signatures/overview.md) ## Electronic signatures --- **Add an ink electronic signature** How to add an electronic signature (eSignature) to a PDF document [Read more](https://www.nutrient.io/guides/ios/signatures/adding-an-electronic-signature.md) --- **Electronic signature storage** How to implement a mechanism for storing signatures [Read more](https://www.nutrient.io/guides/ios/signatures/signature-storage.md) --- **Electronically sign with a certificate** How to use electronic signatures and digital signatures together [Read more](https://www.nutrient.io/guides/ios/signatures/using-electronic-signatures-and-digital-signatures-together.md) ## Digital signatures --- **Supported digital signature methods** Learn about supported digital signing methods and algorithms [Read more](https://www.nutrient.io/guides/ios/signatures/digital-signatures/supported-methods.md) --- **Generate a certificate** How to generate a self-signed certificate for testing purposes [Read more](https://www.nutrient.io/guides/ios/signatures/digital-signatures/generate-certificate.md) --- **Add a digital signature** How to add a digital signature to a PDF document [Read more](https://www.nutrient.io/guides/ios/features/digital-signatures.md) --- **Validate digital signatures** How to validate digital signatures [Read more](https://www.nutrient.io/guides/ios/signatures/digital-signatures/validation.md) --- **Biometric digital signatures** How to create a digital signing solution based on biometric data [Read more](https://www.nutrient.io/guides/ios/signatures/digital-signatures/biometric.md) --- **Digital signature customization** How to customize the digital signing experience [Read more](https://www.nutrient.io/guides/ios/signatures/digital-signatures/customization.md) --- **Custom digital signers** How to sign a document using your own encryption [Read more](https://www.nutrient.io/guides/ios/signatures/digital-signatures/custom-signers.md) --- **Contained digital signatures** Learn about splitting the signing workflow into two phases [Read more](https://www.nutrient.io/guides/ios/signatures/digital-signatures/contained-signatures.md) --- **Legacy built-in digital signatures UI** Learn about the digital signatures UI available before 1 May 2021 [Read more](https://www.nutrient.io/guides/ios/signatures/digital-signatures/built-in-ui.md) ## Combine with forms --- **Add a signature field** How to programmatically add new signature form fields to a PDF [Read more](https://www.nutrient.io/guides/ios/signatures/add-a-signature-field.md) --- **Fill and sign forms** How to programmatically or manually fill and sign forms in a PDF [Read more](https://www.nutrient.io/guides/ios/signatures/fill-and-sign-forms.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 - [Add signature fields to PDFs on iOS](/guides/ios/signatures/add-a-signature-field.md) - [Fill and Sign a PDF Form on iOS](/guides/ios/signatures/fill-and-sign-forms.md) - [Understanding electronic and digital signatures](/guides/ios/signatures/overview.md) ## Pages in this section - [Adding a Digital Signature to a PDF on iOS](/guides/ios/features/digital-signatures.md) - [Biometric Signatures on iOS](/guides/ios/signatures/digital-signatures/biometric.md) - [Contained Digital Signatures on iOS](/guides/ios/signatures/digital-signatures/contained-signatures.md) - [Signatures in iOS Viewer](/guides/ios/signatures/digital-signatures/built-in-ui.md) - [Sign PDFs and Add Custom Encryption on iOS](/guides/ios/signatures/digital-signatures/custom-signers.md) - [Secure digital signatures for iOS PDF libraries](/guides/ios/signatures/digital-signatures/supported-methods.md) - [Troubleshooting](/guides/ios/signatures/digital-signatures/troubleshooting.md) - [Customizing Digital Signatures on iOS](/guides/ios/signatures/digital-signatures/customization.md) - [Generate a Self-Signed Certificate for Signing on iOS](/guides/ios/signatures/digital-signatures/generate-certificate.md) - [Digital Signature Standards: CAdES and PAdES](/guides/ios/signatures/digital-signatures/standards.md) - [Validating a Digital Signature on iOS](/guides/ios/signatures/digital-signatures/validation.md) - [eSign PDFs with a Certificate on iOS](/guides/ios/signatures/using-electronic-signatures-and-digital-signatures-together.md) - [How to add electronic signatures to PDFs on iOS](/guides/ios/signatures/adding-an-electronic-signature.md) - [Save and store electronic signatures on iOS](/guides/ios/signatures/signature-storage.md) - [Understanding digital signature validation states](/guides/ios/signatures/troubleshooting/chain-of-certs-not-valid.md)