DocumentWriter

protocol · iOS 27.0+ · SDK 27.1

protocol DocumentWriter<Snapshot>

A type that writes a document's content to a file. SwiftUI calls your document's ``WritableDocument/snapshot(contentType:)`` on the main actor to capture the current state, then obtains a `DocumentWriter` from ``WritableDocument/writer(configuration:)`` and invokes ``write(content:to:previous:progress:)`` in the background with coordinated file access. Use ``FileWrapperDocumentWriter`` for cases cases that don't require custom file write logic. Implement a `DocumentWriter` when you need direct URL access or streaming writes: struct ImageWriter: DocumentWriter { @concurrent func write(content image: sending CGImage, to destination: URL, previous: sending CGImage?, progress: consuming Subprogress ) async throws { guard let imageDestination = CGImageDestinationCreateWithURL( destination as CFURL, UTType.jpeg.identifier as CFString, 1, nil ) else { throw CocoaError(.fileWriteUnknown) } CGImageDestinationAddImage( imageDestination, image, nil ) guard CGImageDestinationFinalize( imageDestination ) else { throw CocoaError(.fileWriteUnknown) } } }

Members (0)

This type has no directly callable members in this snapshot. See the framework’s skipped declarations for unsupported APIs.

All SwiftUI types →