dragContainer(for:in:_:)

Declaration

nonisolated func dragContainer<Item, Data>(for itemType: Item.Type = Item.self, in namespace: Namespace.ID? = nil, _ payload: @escaping (Array<Item.ID>) -> Data) -> some View where Item : Transferable, Item : Identifiable, Item == Data.Element, Data : Collection, Item.ID : Sendable

Parameters

• itemType:

  A type of the dragged items.

• namespace:

  A namespace that identifies the drag container.

• payload:

  A closure which is called when a drag operation begins. As an argument, the closure receives either the identifiers of all the selected items, if the dragged item is a part of selection or only the identifier of the dragged item, if it is not part of the selection. With the passed identifiers, put together the payload to drag, and return from the closure. Return an empty Collection to disable the drag.

Return Value

A view that can be activated as the source of a drag and drop operation, beginning with user gesture input.

Discussion

Provide the selected identifiers list to SwiftUI using dragContainerSelection(_:containerNamespace) modifier. In a case when there’s no selection information available, SwiftUI passes the dragged item identifier to the payload closure.

In an example below, an app presents a view with Fruit values. When a user starts drag, SwiftUI uses the selection to put together the list of item identifiers to drag.

   var fruits: [Fruit]
   @State private var selection: [Fruit.ID]

   var body: some View {
       VStack {
           ForEach(fruits) { fruit in
               FruitView(fruit)
                   .draggable(containerItemID: fruit.id)
           }
       }
       .dragContainer(for: Fruit.self) { ids in
          fruits(with: ids)
       }
       .dragContainerSelection(selection)
   }

   func fruits(with ids: [UUID]) -> [Fruit] { ... }

   struct Fruit: Transferable, Identifiable { ... }