Code sample #3 from drag&drop tutorial

dragdrop-3.swift

class ViewController: UIViewController, UIDropInteractionDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        view.addInteraction(UIDropInteraction(delegate: self))
    }
    
    func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession) {
    }
    
    func dropInteraction(_ interaction: UIDropInteraction, sessionDidUpdate session: UIDropSession) -> UIDropProposal {
        //The operation that this interaction proposes to perform.
        return UIDropProposal(operation: .copy)
    }
    
    func dropInteraction(_ interaction: UIDropInteraction, canHandle session: UIDropSession) -> Bool {
        //Returns true if any of the session's items could create any objects of the specified class.
        return session.canLoadObjects(ofClass: UIImage.self)
    }
    
}