Batch uploader with UIActivityViewController

ViewController.swift

    override func viewDidLoad() {
        super.viewDidLoad()
        let items: [[Any]] = [
            ["Foo", URL(string: "http://www.africau.edu/images/default/sample.pdf")!]
            ["Bar", URL(string: "http://www.africau.edu/images/default/sample.pdf")!]
        ]
        presentActivityViewControllerRecursively(items: items) { (error, items) in
            if let error = error, let items = items {
                print("Failed to complete activity items: \(items)")
                return
            }
            print("done")
        }
    }

    private func presentActivityViewControllerRecursively(items: [[Any]], completion: @escaping (Error?, [Any]?) -> Void) {
        var _items = items
        let vc = UIActivityViewController(activityItems: _items.remove(at: 0), applicationActivities: nil)
        vc.completionWithItemsHandler = { [weak self] (_, completed, items, error) in
            guard completed else {
                completion(error, items)
                return
            }
            if _items.isEmpty {
                completion(nil, nil)
                return
            }
            self?.presentActivityViewControllerRecursively(items: _items, completion: completion)
        }
        present(vc, animated: true, completion: nil)
    }