Platforms State of the Union

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Platforms State of the Union spends 70 minutes weaving together the four developer threads of WWDC25: the Liquid Glass design language, on-device inference with Foundation Models, Xcode 26 with Swift 6.2, and capability upgrades across SwiftUI, visionOS, and Metal 4.

Core Content

In recent years, the work of adapting an app to Apple platforms has grown heavier. iOS, iPadOS, macOS, watchOS, and visionOS each have their own control look, safe areas, and layout rules. To look good on all five, a developer either writes five sets of UI code or makes compromises. That was the biggest pain point heading into WWDC25.

Apple’s answer in Platforms State of the Union is “unify again.” The new Liquid Glass material treats a control as a functional layer floating above the content. All five platforms share one set of control geometry (corner radii aligned with the hardware) and one set of color rules (auto-inverted against the content beneath). SwiftUI, UIKit, and AppKit all move to Liquid Glass at the same time. Recompile in Xcode 26 and you get the first pass of the new look; then use new APIs like the toolbar spacer and the background extension effect to fine-tune. The whole SOTU follows this “recompile first, refine later” path across six tracks: design, AI, Xcode, SwiftUI, visionOS, and games.

Detailed Content

Liquid Glass and the three design principles (03:00). Billy sums up the new design with three words: hierarchy, harmony, and consistency. Liquid Glass reshapes a control from a rectangle into a form that follows the hardware corner radius. The control itself refracts the content beneath, reflects ambient light, and shows lens distortion at its edges. At (09:27), Taylor lays out a three-step API path: recompile to see the default look, use new APIs to adjust toolbars and navigation, and apply the glassEffect modifier to add Liquid Glass to custom controls. Icon Composer is the new icon editor; it supports vector-layered import and multi-mode preview (light, dark, tinted).

Foundation Models framework (around 20:00). The on-device 3-billion-parameter model is exposed directly to developers: zero inference cost, zero network latency, zero privacy risk. On the Swift side, the @Generable macro turns any struct into the model’s output schema, and @Guide adds field-level constraints (numeric ranges, string patterns). Tool calling lets the model invoke Swift functions during generation, for example calling MapKit to search nearby shops. All calls support streaming output and custom guardrails.

Xcode 26 + Swift 6.2. Xcode ships a built-in model panel: ChatGPT by default, switchable to Claude, Anthropic, or a local LLM. Coding Tools extends the Apple Intelligence Writing Tools experience to code: select a function, and the menu generates unit tests or doc comments on the spot. The #Playground macro lets any Swift file run non-UI code live, much like SwiftUI Preview, which is handy for iterating on Foundation Models prompts. Swift 6.2 brings inline arrays (fixed-length arrays on the stack), span types (a safe view over contiguous memory), stronger C++ interop, a WebAssembly compile target, and the new open-source Containerization framework that runs Linux containers natively on Mac.

SwiftUI, visionOS, Metal 4. SwiftUI adds a WebView component, a rich text editor control, and 3D Charts, and loads 100,000-row lists 6x faster. visionOS 26 introduces volumetric APIs, nearby window sharing, WidgetKit support, and the ability to turn any 2D photo into a 3D spatial scene. Metal 4 lets shaders run neural networks for lighting and material inference, and MetalFX adds frame interpolation. On stage, an M4 MacBook Air ran Cyberpunk 2077 at a steady 60fps.

Key Takeaways

• Adapt to Liquid Glass in two steps: recompile in Xcode 26 to see the default look, then fine-tune toolbars, custom backgrounds, and custom borders one by one with the new APIs.
  • Why it pays off: many hand-drawn rounded backgrounds and translucent cards can be deleted and handed back to the system’s Liquid Glass, cutting code and adapting to light and dark mode automatically.
  • How to start: build once in Xcode 26, list the diffs against your old screenshots, and replace each view with glassEffect.
• Iterate Foundation Models prompts in the Playground macro first: edit the prompt and watch the output inside #Playground; promote to real code only once it is stable.
  • Why it pays off: on-device inference is free to call, so you iterate an order of magnitude faster than against a remote API, with no user quota burned.
  • How to start: create a Swift file, write #Playground { ... }, call LanguageModelSession inside, and tweak the prompt repeatedly.
• Server-side Swift teams should try the Containerization framework today: running Linux containers on Mac no longer needs Docker Desktop.
  • Why it pays off: native Apple silicon performance, no license cost, and a shorter CI/CD chain.
  • How to start: clone Apple’s official Containerization repo, run the sample nginx container, and port your service’s Dockerfile.
• Game developers should watch Metal 4 neural rendering: shaders can call inference networks to compute lighting and materials.
  • Why it pays off: image quality goes up sharply with no extra video memory budget, opening a new performance curve beyond ray tracing.
  • How to start: read the neural shading chapter in the Metal 4 docs, and validate the win on a small scene with MetalFX frame interpolation first.

Related Sessions

• Keynote — The main-stage WWDC25 announcement, an overview of new products and system features for all users.
• Meet Liquid Glass — The principles, materials, and control details of the Liquid Glass design language.
• Meet the Foundation Models framework — An intro to the on-device LLM Swift framework, with Generable and Tool calling.
• What’s new in Swift — Swift 6.2’s inline arrays, span, C++ interop, and concurrency improvements.
• What’s new in SwiftUI — SwiftUI updates across WebView, rich text, 3D Charts, and performance.