swiftdata-transferrable

This package implements generic extensions to the .draggable() and .dropDestination() SwiftUI View modifiers to faclilitate direct Drag and Drop operations with SwiftData PersistentModel objects.

Since SwiftData PersistentModel objects are not Codable and they are not Transferable, instead of trying to drag and drop the PersistentModel objects themselves, this package extracts and drags the PersistentIdentifier struct from the corresponding PersistentModel object. This works well for dragging because the PersistentIdentifier struct is already Codable and it can easily be made Transferable. The PersistentIdentifier struct also works well for dropping because it can be used to retrieve its corresponding PersistentModel object from the ModelContext.

A complete project that demonstrates how to use this package is available at: https://github.com/Whiffer/SampleSwiftDataTransferrable

Steps to Implement SwiftUI Drag and Drop with SwiftData objects

Add a Package Dependency for this package to your project

The Package URL is: https://github.com/Whiffer/swiftdata-transferrable

Create an appropriate Exported Type Identifier for your project

Open your project settings, select the Info tab for your Target, then add a new Exported Type Identifier with the following properties:

Description:    "SwiftData Persistent Model ID"
Identifier:     "com.YourTeam.persistentModelID"
Conforms To:    "public.data"

Add the SwiftDataTransferrableScene Scene

Add a SwiftDataTransferrableScene SceneBuilder with appropriate argument values to your App struct. Include all Scene's that have View's that you wish to use with this package.

        SwiftDataTransferrableScene(schema: schema, exportedUTType: "com.YourTeam.persistentModelID") {
            WindowGroup {
                ContentView()
            }
        }

Add .draggable() View modifiers

The syntax of this package's generic PersistentModel .draggable() View modifier is the same as SwiftUI's generic Transferrable .draggable() View modifier. Just supply the View modifier with the PersistentModel object to be dragged.

        Text("\(item.description) Drag Source Item")
        .draggable(item)

Add .dropDestination() View modifiers

The syntax for this package's generic PersistentModel dropDestination() View modifier is the same as SwiftUI's generic Transferrable .dropDestination() View modifier. The PersistentModel items being dropped are the same PersistentModel objects that were dragged by the .draggable() View modifier.

        Text("Drop Target")
        .dropDestination(for: Item.self) { items, _ in
            for item in items {
                print("\(item.description) dropped on Drop Target")
            }
            return true
        }

Change History

The .swiftDataTransferrable() View modifier is no longer available in Version 3.0 of this package. Instead, use SwiftDataTransferrableScene() as described above by providing it with your WindowGroup(s). The SwiftDataTransferrableScene() includes all of the necessary SwiftData model container setup that was formerly required to be provided in your App struct.

The dropPropsal parameter is no longer available in Version 2.0 of this package.

In addition to the standard for:, action:, and isTargeted: paramenters, there is a new dropProposal: parameter to pass an optional closure that allows saving of a DropProposal struct during the drag and before the drop. It is also used to inform the DropDelegate of the currently proposed DropOperation (e.g. .copy, .move and .forbidden). There are examples of how to use this feature in the sample program linked above.