WWDC 2026 for devs (part 3): Xcode Agent Skills and the official SwiftUI APIs

Third (and for now final) installment of the WWDC 2026 developer recap. The earlier ones: part 1 (the essentials) and part 2 (AI in apps and agents). Now that Apple has published the official guides, we use them to sharpen API names and cover what was missing — starting with the least-talked-about gem: Xcode’s Agent Skills.

Note: with official docs up, several names are now confirmed; still, this is beta material and may change.

Xcode 27: Agent Skills

Maybe the most interesting thing for day-to-day work. Agent Skills are guidance packages you give Xcode’s agent for the areas where models tend to fail: brand-new APIs they’ve barely seen, recently deprecated patterns they keep reaching for, and platform-specific footguns. (DEV Community)

Xcode 27 ships seven skills authored by Apple:

swiftui-specialist — writing idiomatic SwiftUI.
swiftui-whats-new-27 — the new SwiftUI APIs from this cycle.
uikit-app-modernization — modernizing UIKit code to current patterns.
test-modernizer — updating tests to current practices.
audit-xcode-security-settings — reviewing the project’s security configuration.
c-bounds-safety — C bounds-safety guidance.
device-interaction — working with devices and simulators.

The agent loads the right skill based on what you ask (e.g., swiftui-whats-new-27 when adopting a new API, or audit-xcode-security-settings when reviewing config). You can export them to inspect them:

xcrun agent skills export --output-dir ~/Downloads/xcode-skills

And the best part: you can author your own with the same format — a folder with a SKILL.md that carries YAML metadata and your project-specific guidance:

---
name: internal-api
description: How to use our internal networking layer
---

Always use `APIClient.shared`. Don't instantiate `URLSession` by hand.
Responses decode with `APIDecoder`, never with a raw `JSONDecoder`.

That way the agent follows your conventions, not just the generic ones. (If this sounds like the “skills” pattern from other agents, it’s exactly that idea, built into Xcode.)

SwiftUI, with official names

Apple’s official SwiftUI guide confirms and sharpens what came from blogs in the earlier parts. The highlights, with exact names:

Adaptive toolbars: visibilityPriority, toolbarOverflowMenu, topBarPinnedTrailing, and a new toolbarMinimizeBehavior (collapse the bar on scroll).
Documents: ReadableDocument and WritableDocument protocols for direct structure control, asynchronous, incremental disk operations, progress reporting via Foundation’s Subprogress, and DocumentCreationSource + NewDocumentButton for multiple creation sources.
Reordering and swipe: reorderable containers in List, LazyVGrid, and custom layouts (and now on watchOS too); swipeActionsContainer for ScrollView.
Binding-driven alerts/dialogs: they present themselves when the bound value is set (item-binding pattern for alert/confirmationDialog).
Performance: AsyncImage respects standard HTTP caching by default (reads the server’s headers) and asyncImageURLSession lets you configure your own URLRequest/URLSession; @State becomes a macro with lazy initialization; and ViewBuilder is exposed as ContentBuilder to improve build times.

Swift 6.3 and 6.4

Worth noting that two versions actually landed (6.3 and 6.4) with a common thread: less boilerplate, fewer surprises, and more control — language, library, cross-platform, and performance improvements. (In part 1 we covered the concrete 6.4 changes.)

Sessions to watch

If you’re going to go deep on just one thing, these two:

That wraps our WWDC 2026 developer coverage (part 1 · part 2 · part 3). If anything changes meaningfully when the final releases ship, we’ll note it.

👉 Part 4 is out: visionOS, Siri’s shift, and the rest of the ecosystem.

Sources: Apple — WWDC26 SwiftUI guide · Apple — What’s new in SwiftUI (269) · Apple — What’s new in Xcode 27 (258) · DEV Community — Xcode 27 Agent Skills