近日在開發歲寒輸入法的主題功能，為了實現導出主題包功能，頗費一番周折，最終代碼也不復雜，我在本文中簡單作個介紹。

我這里仍然是要使用DependencyService.

聲明接口

namespace SuiHanLib {
    public interface IOutputTheme {
        void output(string path);
    }
}

在iOS項目中實現

using System;
using SuiHanLib;
using Foundation;
using UIKit;

[assembly: Xamarin.Forms.Dependency(typeof(SuiHanIME.iOS.OutputTheme_iOS))]
namespace SuiHanIME.iOS {
    public class OutputTheme_iOS : IOutputTheme {
        public OutputTheme_iOS() {
        }

        public void output(string path) {
            var nSUrl = NSUrl.FromFilename(path);
            var viewer = UIDocumentInteractionController.FromUrl(nSUrl);
            viewer.Uti = @"public.archive";//聲明文件的類型
            var controller = GetVisibleViewController();
            viewer.PresentOpenInMenu(controller.View.Frame, controller.View, true);
        }

        // Search recursively for the top most UIViewController
        // Source: http://stackoverflow.com/questions/41241508/xamarin-forms-warning-attempt-to-present-on-whose-view-is-not-in-the-window
        private UIViewController GetVisibleViewController(UIViewController controller = null) {
            controller = controller ?? UIApplication.SharedApplication.KeyWindow.RootViewController;

            if (controller.PresentedViewController == null)
                return controller;

            if (controller.PresentedViewController is UINavigationController) {
                return ((UINavigationController)controller.PresentedViewController).VisibleViewController;
            }

            if (controller.PresentedViewController is UITabBarController) {
                return ((UITabBarController)controller.PresentedViewController).SelectedViewController;
            }

            return GetVisibleViewController(controller.PresentedViewController);
        }

    }
}

使用方法

    var openControl = DependencyService.Get<IOutputTheme>();
    openControl.output(path);//path為文件的完整路徑

最終效果

注意：在虛擬機下是打不開導出菜單的，要在真機才行。