Code sample #3 from drag&drop tutorial

dragdrop-4.swift

func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession) {
    for dragItem in session.items { // (1)
	// (2)
	dragItem.itemProvider.loadObject(ofClass: UIImage.self, completionHandler: { object, error in
	    // (3)			
	    guard error == nil else { return print("Failed to load our dragged item") }
	    guard let draggedImage = object as? UIImage else { return } // (4)
				
	    DispatchQueue.main.async { // (5)
		let imageView = UIImageView(image: draggedImage) // (6)
		self.view.addSubview(imageView)
		imageView.frame = CGRect(x: 0, y: 0, width: draggedImage.size.width, height: draggedImage.size.height)
					
		let centerPoint = session.location(in: self.view)
		imageView.center = centerPoint
	    }
	})
    }
}