--- title: Apple Improves Context Window Management for its... description: iOS 26.4 RC introduces new context window management tools for Apple's on-device Foundation Models framework. The update adds a `contextSize` property on... canonical: https://daily.dev/posts/apple-improves-context-window-management-for-its-foundation-models-cx419bigo twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Apple Improves Context Window Management for its Foundation Models | daily.dev og:description: iOS 26.4 RC introduces new context window management tools for Apple's on-device Foundation Models framework. The update adds a `contextSize` property on... og:url: https://daily.dev/posts/apple-improves-context-window-management-for-its-foundation-models-cx419bigo og:image: https://api.daily.dev/og/posts/CX419bigo.png og:image:alt: Apple Improves Context Window Management for its Foundation Models og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Apple Improves Context Window Management for its Foundation Models **[InfoQ](https://daily.dev/sources/infoq)** · 3 min read · 0 upvotes · 0 comments ## Summary iOS 26.4 RC introduces new context window management tools for Apple's on-device Foundation Models framework. The update adds a `contextSize` property on `SystemLanguageModel` and a `tokenCount(for:)` method, enabling developers to dynamically track and manage the 4096-token context window limit without hardcoding values. Key challenges include accounting for system prompts, user instructions, and tool definitions (which serialize their schemas and inflate token counts). These additions are back-deployed to all iOS versions supporting the framework, and Apple recommends strategies like session splitting, prompt trimming, and requesting shorter model responses to avoid `.exceededContextWindowSize` errors. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Managing Small Context Windows in Language Models](https://daily.dev/posts/managing-small-context-windows-in-language-models-n3u1axvbz) · Machine Learning Mastery · 1 upvotes · 0 comments --- Tags: [#ai](https://daily.dev/tags/ai), [#llm](https://daily.dev/tags/llm), [#apple](https://daily.dev/tags/apple), [#swift](https://daily.dev/tags/swift) [View this post on daily.dev](https://daily.dev/posts/apple-improves-context-window-management-for-its-foundation-models-cx419bigo) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Apple Improves Context Window Management for its Foundation Models","url":"https://daily.dev/posts/apple-improves-context-window-management-for-its-foundation-models-cx419bigo","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/apple-improves-context-window-management-for-its-foundation-models-cx419bigo"},"datePublished":"2026-03-23T11:02:57.803Z","dateModified":"2026-08-24T07:10:31.864Z","description":"iOS 26.4 RC introduces new context window management tools for Apple's on-device Foundation Models framework. 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