With closure

tableViewController2.swift

struct SelectedTagDetail {
    var id: Int = 0
    var name: String = ""
}

typealias SelectedTagsClosure = (tags: [SelectedTagDetail]) -> Void

class BudgetTagsTableViewController: UITableViewController, BNDTableViewProxyDataSource {
    // ...
    var selectedTagIDs = Set<Int>()
    var onCloseSelectedTags: SelectedTagsClosure?
    // ...
    
    override func viewWillDisappear(animated: Bool) {
        if self.isMovingFromParentViewController() && self.onCloseSelectedTags != nil {

            let selected = self.dataArray.filter({self.selectedTagIDs.contains($0.id)})
            let detailList = selected.map{ (tag) -> SelectedTagDetail in
                return SelectedTagDetail(id: tag.id, name: tag.tag)
            }
            self.onCloseSelectedTags?(tags: detailList)
        }
    }
    // ...
}