当使用swift3.0进行按钮操作时，如何在ios mobile中打开文档文件，例如（.pdf，.doc，.docx）？

我需要打开 UIDocumentPickerViewController ，它应该允许用户选择所有类型的文件。 ie。（。pdf，.doc）文件我用 UIDocumentPickerViewController 方法。
我的代码：

I need to open UIDocumentPickerViewController and It should allow user to select all type of files. ie.(.pdf,.doc)files I used UIDocumentPickerViewController method. my Code:

我的班级声明中的UIDocumentPickerDelegate，UIDocumentMenuDelegate

//上传文件

func OpenFile(){

    let importMenu = UIDocumentMenuViewController(documentTypes: [String(kUTTypePNG),String(kUTTypeImage)], in: .import)
    importMenu.delegate = self
    importMenu.modalPresentationStyle = .fullScreen
    self.present(importMenu, animated: true, completion: nil)

}
@available(iOS 8.0, *)
public func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentAt url: URL) {        
    let cico = url as URL
    print("The Url is : \(cico)")

    do {
        let weatherData = try NSData(contentsOf: cico, options: NSData.ReadingOptions())
        print(weatherData)
        let activityItems = [weatherData]
        let activityController = UIActivityViewController(activityItems: activityItems, applicationActivities: nil)
        if UI_USER_INTERFACE_IDIOM() == .phone {
            self.present(activityController, animated: true, completion: { _ in })
        }
        else {
            let popup = UIPopoverController(contentViewController: activityController)
            popup.present(from: CGRect(x: CGFloat(self.view.frame.size.width / 2), y: CGFloat(self.view.frame.size.height / 4), width: CGFloat(0), height: CGFloat(0)), in: self.view, permittedArrowDirections: .any, animated: true)
        }

    } catch {
        print(error)
    }

    //optional, case PDF -> render
    //displayPDFweb.loadRequest(NSURLRequest(url: cico) as URLRequest)      


}

@available(iOS 8.0, *)
public func documentMenu(_ documentMenu:     UIDocumentMenuViewController, didPickDocumentPicker documentPicker: UIDocumentPickerViewController) {

    documentPicker.delegate = self
    present(documentPicker, animated: true, completion: nil)        
} 


func documentPickerWasCancelled(_ controller: UIDocumentPickerViewController) {

    print(" cancelled by user")

    dismiss(animated: true, completion: nil)        

}

在此代码中应用程序会崩溃。原因是由于未捕获的异常'NSInvalidArgumentException'而终止应用程序，原因：'除了initWithDocumentTypes之外，你无法初始化UIDocumentPickerViewController：inMode：和initWithURL：inMode：initializers。

In this code the app will crash. the reason is Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'You cannot initialize a UIDocumentPickerViewController except by the initWithDocumentTypes:inMode: and initWithURL:inMode: initializers.

我不知道如何初始化 initWithDocumentTypes：inMode。我是iOS的新手，任何人帮助我？ ??
你可以帮帮我..

I don't know how to initialise the initWithDocumentTypes:inMode. I'm new to iOS any one help me??? can you please help me..