Build A SwiftUI Document App With WritableDocument

This article explains how to build a SwiftUI document-based app using the new WritableDocument API introduced in the WWDC26 beta cycle. It covers the shift from synchronous FileWrapper-based saving to a snapshot-based model where the main-actor document provides a sendable snapshot, and an async DocumentWriter handles disk writes. The tutorial walks through creating a sketch and sticker board app with custom document package format and export to PNG/PDF. It includes code examples for setting up DocumentGroup, custom launch scenes with creation sources, and handling document configuration and context. The article is relevant to iOS, iPadOS, macOS, and visionOS developers working with SwiftUI document APIs.