# DataRepresentation A transfer representation for types that provide their own binary data conversion. ``` struct DataRepresentation where Item : Transferable ``` ## Overview Use this transfer representation if your model is stored in memory. For example, a drawing app might have a notion of a *layer* that can be converted to and from a custom binary data format and also converted to the PNG image type: ``` struct ImageDocumentLayer { init(data: Data) throws { } func data() -> Data { Data() } func pngData() -> Data { Data() } } ``` You can provide multiple transfer representations for a model type, even if the transfer representation types are the same. The following shows the `ImageDocumentLayer` structure conforming to `Transferable` with two [`DataRepresentation`](/documentation/CoreTransferable/DataRepresentation) instances composed together: ``` extension ImageDocumentLayer: Transferable { static var transferRepresentation: some TransferRepresentation { DataRepresentation(contentType: .layer) { layer in layer.data() } importing: { data in try ImageDocumentLayer(data: data) } DataRepresentation(exportedContentType: .png) { layer in layer.pngData() } } } ``` The example drawing app’s custom transfer representation comes first so that apps that know about the custom transfer representation can use it. The second transfer representation offers export compatibility with other apps that work with PNG images. Avoid registering data with the `UTType.data` content type. Instead, choose a content type that best describes the data structure. For example, register PDF data with `UTType.pdf` so the data can be dragged, shared, or imported to apps that support that data type: ``` struct PDFDocument: Transferable { var pdfData: Data static var transferRepresentation: some TransferRepresentation { DataRepresentation(contentType: .pdf) { pdfDocument in pdfDocument.pdfData } importing: { data in PDFDocument(pdfData: data) } } ``` > Tip: If a type conforms to `Codable`, ``doc://com.apple.CoreTransferable/documentation/CoreTransferable/CodableRepresentation`` might be > a more convenient choice than `DataRepresentation`. ## Topics ### Creating a transfer representation [`init(contentType:exporting:importing:)`](/documentation/CoreTransferable/DataRepresentation/init(contentType:exporting:importing:)) Creates a representation that allows transporting an item as binary data. [`init(importedContentType:importing:)`](/documentation/CoreTransferable/DataRepresentation/init(importedContentType:importing:)) Creates a representation that allows importing an item as binary data. [`init(exportedContentType:exporting:)`](/documentation/CoreTransferable/DataRepresentation/init(exportedContentType:exporting:)) Creates a representation that allows exporting an item as binary data. ### Implementing a transfer representation --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)