Custom drag and drop view

Question

I set mine UITableViewto use the new drag and drop APIs.

if #available(iOS 11, *) {
    self.tableView.dragDelegate = self
    self.tableView.dropDelegate = self
    self.tableView.dragInteractionEnabled = true
    navigationController?.navigationBar.prefersLargeTitles = false
}

Now I have applied the method below to be able to use custom views for d & d.

@available(iOS 11.0, *)
func dragInteraction(_ interaction: UIDragInteraction, previewForLifting item: UIDragItem, session: UIDragSession) -> UITargetedDragPreview? {
    print("Custom Preview method called!")
    let test = UITextView.init(frame: CGRect.init(x: 0, y: 0, width: 200, height: 200))
    test.text = "sfgshshsfhshshfshsfh"
    let dragView = interaction.view!
    let dragPoint = session.location(in: dragView)
    let target = UIDragPreviewTarget(container: dragView, center: dragPoint)
    return UITargetedDragPreview(view: test, parameters:UIDragPreviewParameters(), target:target)
}

However, this method is never called. I never see print()or my user view. Any ideas on what I'm doing wrong?

Answer 1

You must set the property previewProviderwhen creating the UIDragItem.

let dragItem = UIDragItem(...)
dragItem.previewProvider = {
    print("Custom Preview method called!")
    let test = UITextView.init(frame: CGRect.init(x: 0, y: 0, width: 200, height: 200))
    test.text = "sfgshshsfhshshfshsfh"
    return UIDragPreview(view: test)
}

See: https://developer.apple.com/documentation/uikit/uidragitem/2890972-previewprovider?language=objc

Answer 2

iPhone? , UIViewController 25 2017 :

• Apple iPad.
• dragInteraction ,
• (.. iPhone).
• iPhone 8

dragInteractionEnabled UITableViewController UICollectionViewController. iPhone false , , UIViewController.