Until I Write A Blog Post, This Gist Will Do, by Fall Out Boy

trasnferable-swiftdata.swift

//
//  TransferablePersistentID.swift
//  Cabinette
//
//  Created by Peter Kos on 3/1/24.
//

import CoreTransferable
import SwiftData
import UniformTypeIdentifiers

/// Wrapper around SwiftData PersistentID that conforms to Codable,
/// so we can drag/drop a model using its ID as the transfer.
///
/// Note: was unable to get this working with generics. Creating a
/// phantom protocol `DragContentType` was not enough to
/// make `.dropDestination` distinguish between them.
///
class TransferablePersistentAlbumID: Codable {
    var persistentID: PersistentIdentifier
    init(_ id: PersistentIdentifier) {
        persistentID = id
    }
}

class TransferablePersistentTrackID: Codable {
    var persistentID: PersistentIdentifier
    init(_ id: PersistentIdentifier) {
        persistentID = id
    }
}

extension TransferablePersistentAlbumID: Transferable {
    static var transferRepresentation: some TransferRepresentation {
        CodableRepresentation(for: TransferablePersistentAlbumID.self, contentType: .persistentAlbumID)
    }
}

extension TransferablePersistentTrackID: Transferable {
    static var transferRepresentation: some TransferRepresentation {
        CodableRepresentation(for: TransferablePersistentTrackID.self, contentType: .persistentTrackID)
    }
}

extension UTType {
    static var persistentAlbumID: UTType {
        UTType(exportedAs: "me.peterkos.cabinette.persistentalbumid")
    }

    static var persistentTrackID: UTType {
        UTType(exportedAs: "me.peterkos.cabinette.persistenttrackid")
    }
}