ios - 为什么 UIDocumentMenu 委托(delegate)给自己不起作用？

Question

我正在关注 UIDocumentMenuViewController 的 Apple 文档，以下是我的代码。 importMenu.delegate = self 不起作用并且 Xcode 显示:无法将类型“ViewController”的值分配给类型“UIDocumentMenuDelegate？” .请帮忙。谢谢!

import UIKit

class ViewController: UIViewController  {

override func viewDidLoad() {
    super.viewDidLoad()

    let importMenu = UIDocumentMenuViewController(documentTypes: ["public.text", "public.data"], inMode: .Import)

    importMenu.delegate = self

    self.presentViewController(importMenu, animated: true, completion: nil)

   }
}

Answer 1

根据 UIDocumentMenuDelegate Protocol Reference ，您的 ViewController 必须符合 UIDocumentMenuDelegate 并且必须实现 documentMenu:didPickDocumentPicker:

extension ViewController: UIDocumentMenuDelegate {
    func documentMenu(documentMenu: UIDocumentMenuViewController, didPickDocumentPicker documentPicker: UIDocumentPickerViewController) {
        // do stuffs here
    }
}