출처

• The app from which an item is dragged is called the source app.
• The app on which an item is dropped is called the destination app.

For drag and drop in a single app, that app plays both roles simultaneously.

= 하나의 app에서 drag and drop으로 이뤄질 경우 source/destination 두가지의 역할 모두를 해야함

Drag and Drop & TableView

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• drag and drop을 사용하기 위해서는 tableView 자체를 drag/drop delegate로 지정해야함
• data를 제공/사용하기 위해서는 drag/drop delegate method들을 구현해야함
• tableView/customView의 drag/drop은 좀 다름

Enable Drag and Drop Interactions

override func viewDidLoad() {
    super.viewDidLoad()
    
    tableView.dragInteractionEnabled = true
    tableView.dragDelegate = self
    tableView.dropDelegate = self

    navigationItem.rightBarButtonItem = editButtonItem
}

• source/destination이 동일한 tableView이므로 drag/drop delegate를 모두 self로 지정

• tabelView에 drag/drop delegate 객체가 따로 존재

UITableView 문서를 확인해보면