Drag & Drop on iOS14 doesn't work

Question

Created Jul ’20

Replies 6

Boosts 0

Views 3.3k

Participants 7

I am experimenting with drag & drop to later include it in my app.

I come up with a working solution which allows to drag an item from a VStack and it works just fine on iOS 13.5.

Unfortunately, the same code doesn't work on iOS 14.0 simulator (Xcode 12 beta 3).

iOS 13.5: On Item drop, first loadData is called and then object is called and providers in onDrop contains an item

iOS 14.0: On Item drop no functions are called and providers in onDrop is empty

I am not able to figure out if iOS 14.0 requires additional code or this is an issue of iOS 14.

Any idea?

Code Block struct ContentView: View {
    @ObservedObject var model = Model()
    var body: some View {
        HStack {
            Spacer()
            VStack {
                ForEach(model.items, id: \.name) { item in
                    ItemView(item: item)
                }
            }
            Spacer()
            DropView().environmentObject(model)
        }
    }
}
struct ItemView: View {
    var item: Item
    var body: some View {
        Text(item.name)
            .onDrag({
                    NSItemProvider(object: self.item)
                })
    }
}
struct DropView: View {
    @EnvironmentObject var model: Model
    var body: some View {
        Text("Drop Here")
            .onDrop(of: [Item.typeIdentifier], isTargeted: nil) { providers, position in
                print("providers \(providers) position \(position)")
                guard let provider = providers.first(where: { provider in provider.hasItemConformingToTypeIdentifier(Item.typeIdentifier) })
                else {
                    return false
                }
                provider.loadObject(ofClass: Item.self) { reading, _ in
                    guard let item = reading as? Item else {
                        return
                    }
                    DispatchQueue.main.async {
                        self.model.items.removeAll(where: { a in a.name == item.name })
                    }
                }
                return true
            }
    }
}
class Model: ObservableObject {
    @Published var items = [
        Item(name: "Item 1"),
        Item(name: "Item 2"),
        Item(name: "Item 3"),
        Item(name: "Item 4"),
    ]
}
class Item: NSObject {
    public static let typeIdentifier = "dnd.item"
    var name: String
    init(name: String) {
        self.name = name
        super.init()
    }
}

Boost

Answer 1

texasexile OP

Aug ’20

I'm having the same problem too. Drop doesn't call call performDrop() in the Drop Delegate. Like you I'm using SwiftUI. I'll post back if I figure it out.

Are you seeing in the console the message "PBItemCollectionServicer connection disconnected."?

2

Answer 2

huntercmeyer OP

Sep ’20

I am also having this issue, with the same console message as @texasexile. My code:

Code Block Swiftstruct ContentView: View {
	@State private var names: [NSString] = ["John","Hunter","Mark","Tom","Jeremy","Bill","Frank"]
	@State private var isTargeted: Bool = false
	let string = NSString("Test")
	var body: some View {
		GeometryReader { g in
			VStack(alignment: .leading) {
				ForEach(names, id: \.self) { name in
					HStack {
						Text(name as String)
							.padding()
						Spacer()
					}
					.border(Color.black)
					.onDrag {
						NSItemProvider(item: name, typeIdentifier: UTType.modelName.identifier)
					}		
				}
			}
			.onDrop(of: [UTType.modelName], delegate: Delegate(list: $names))
			.padding()
		}
	}
}
struct Delegate: DropDelegate {
	@Binding var list: [NSString]
	func performDrop(info: DropInfo) -> Bool {
		guard info.hasItemsConforming(to: [UTType.modelName]) else {
			return false
		}
		let providers = info.itemProviders(for: [UTType.modelName])
		if let provider = providers.first {
			provider.loadItem(forTypeIdentifier: UTType.modelName.identifier) { (name: NSSecureCoding?, error: Error?) in
				if let name = name as? NSString {
					list.append(name)
					/* This part isn't finished */
				}
			}
		}
		return true
	}
}
extension UTType {
	static let modelName: UTType = UTType("model.name")!
}

I am using NSString in this example, but I'm only doing this to test with a type conforming to NSSecureCoding since I was having issues in a more complicated sample.

1

Answer 3

CSISafeLiving OP

Sep ’20

Hello there,

I'm obtaining the same result using Objective-C UICollectionView: "PBItemCollectionServicer connection disconnected." is shown.

Any update?

1

Answer 4

em_iot OP

Oct ’20

The same problem in my app, any of you guys has already found solution?

1

Answer 5

drewster OP

Oct ’20

Having the same issue. SwiftUI. The implementation works nicely in iOS 13.x, but the drops don't work in iOS 14.

1

Answer 6

paulos OP

Feb ’21

Same issue here! Need a fix for this, it also affects this thread:

https://stackoverflow.com/questions/62606907/swiftui-using-ondrag-and-ondrop-to-reorder-items-within-one-single-lazygrid/65530889#65530889

1