iOS 27 introduces NSTextViewportRenderingSurface and NSTextViewportRenderingSurfaceKey protocols, and makes UITextView/NSTextView conform to NSTextViewportLayoutControllerDelegate — enabling developers to override viewport layout lifecycle methods to build rich extensions like line-number gutters without leaving the safety of framework text views.
• UITextView and NSTextView now conform to NSTextViewportLayoutControllerDelegate, exposing willLayout, configureRenderingSurface, and didLayout as overridable methods in subclasses — this was not possible before iOS 27.
• New NSTextViewportRenderingSurface protocol provides a unified abstraction for the visual elements (UIView, NSView, CALayer) that render layout fragments inside the viewport.
• New NSTextViewportRenderingSurfaceKey protocol allows layout fragments and other objects to serve as stable cache keys mapping to rendering surfaces across layout cycles.
• renderingSurfaceFor(_:) method on NSTextViewportLayoutController lets you query the rendering surface for a given key after layout completes.
• UITextView and NSTextView now expose viewport layout delegate methods via subclassing, so you can react to every layout cycle (scroll, edit, selection) without building a fully custom text view from scratch.
• NSTextViewportRenderingSurface gives you a unified protocol to track and cache the views/layers that render each layout fragment, making custom decorations (gutters, highlights, overlays) far easier to implement.
• These APIs close the long-standing gap between framework-text-view convenience and custom-text-view control, eliminating the need to reimplement text input, accessibility, undo/redo, and dictation just to add layout-aware UI.
Liquid Glass is Apple's new material and visual design language introduced in iOS 27, bringing translucent, refractive glass-like surfaces to system and custom UI elements. It replaces the frosted vibrancy aesthetic with a more dynamic, depth-aware material that responds to content beneath it.
PaperKit is Apple's full-featured canvas framework — previously internal-only — now publicly available in iOS/macOS/visionOS 27. It powers the drawing and markup experience in Notes, Preview, and Freeform, giving developers access to a complete pencil, shapes, images, and text canvas with a rich data model.
Xcode 27 introduces a fully customizable toolbar and theme system, untitled scratch projects, coding agent integration directly in the editor, and the new Device Hub for evaluating apps across simulators and physical devices side-by-side.
In-depth guide
SwiftUI & Liquid Glass in iOS 27 →iOS 27 introduces new SwiftUI drag and drop APIs including reorderable, reorderContainer, dragContainer, and configuration modifiers that enable reordering within and across collections, multi-item drag, and fine-grained control over how data is transferred during drag and drop operations.