---
title: "Saving data externally"
canonical_url: "https://www.nutrient.io/guides/ios/memory-and-storage/saving-data-externally/"
md_url: "https://www.nutrient.io/guides/ios/memory-and-storage/saving-data-externally.md"
last_updated: "2026-06-08T16:48:26.908Z"
description: "By default, Nutrient tries to save annotations into PDFs. If this fails (e.g. if the file is in a nonwritable location), it’ll use the fallback store."
---

By default, Nutrient tries to save annotations into PDFs. If this fails (e.g. if the file is in a nonwritable location), it’ll use the fallback store. This store is located at `/Library/PrivateDocuments/PSPDFKit`.

Each document is referenced by its unique `UID`. Annotations are saved as binary objects.

Next, there’s the image cache at `/Library/Caches/PSPDFKit`. You can control if and how much is saved by customizing the global [`PDFCache`](https://www.nutrient.io/api/ios/documentation/pspdfkit/pdfcache) object. This folder is also cleared when a device is running low on memory.

Lastly, some external data is saved in `/tmp/PSPDFKit`. This data mostly consists of video files that need to be unpacked before they can be displayed. This filter will be cleaned up by the OS on every cold boot of the device or in low memory situations.
---

## Related pages

- [Carthage integration](/guides/ios/best-practices/carthage-integration.md)
- [Nightly Builds](/guides/ios/best-practices/nightly-builds.md)
- [Reduce App Size](/guides/ios/best-practices/reduce-app-size.md)
- [Transferring File Edits To A Server](/guides/ios/best-practices/transferring-file-edits-to-a-server.md)
- [Using Automatic Saving Safely](/guides/ios/best-practices/using-automatic-saving-safely.md)
- [Version Numbering](/guides/ios/best-practices/version-numbering.md)
- [Customizing The Page Number](/guides/ios/customizing-pdf-pages/customizing-the-page-number.md)
- [Bitcode](/guides/ios/faq/bitcode.md)
- [Framework Size](/guides/ios/faq/framework-size.md)
- [iOS PDF SDK security](/guides/ios/faq/sdk-security.md)
- [Strategies For Multiple Bundle Ids](/guides/ios/faq/strategies-for-multiple-bundle-ids.md)
- [Manage your iOS status bar with view controllers](/guides/ios/faq/view-controller-based-status-bar-appearance.md)
- [Airdrop](/guides/ios/features/airdrop.md)
- [Customizing the log level on iOS](/guides/ios/features/logging.md)
- [Modifying permissions in your iOS app](/guides/ios/getting-started/permissions.md)
- [Using Document Efficiently](/guides/ios/getting-started/using-document-efficiently.md)
- [About Memory Usage](/guides/ios/memory-and-storage/about-memory-usage.md)
- [Advanced Carthage integration](/guides/ios/miscellaneous/advanced-carthage-integration.md)
- [Advanced CocoaPods integration](/guides/ios/miscellaneous/advanced-cocoapods-integration.md)
- [Optimize PDF documents for mobile rendering on iOS](/guides/ios/miscellaneous/optimize-pdf-documents-for-mobile-rendering.md)
- [Powered By Nutrient](/guides/ios/miscellaneous/powered-by-nutrient.md)
- [Third Party Compatibility](/guides/ios/miscellaneous/third-party-compatibility.md)
- [Youtube Links](/guides/ios/miscellaneous/youtube-links.md)
- [App Transport Security](/guides/ios/pspdfkit-instant/app-transport-security.md)