c# – Xamarin – 无法找到类型或命名空间名称“App”

"AppDelegate.cs(1,1): error: The type or namespace name 'App' could not be found (are you missing a using directive or an assembly reference?)"

我的解决方案构建没有错误,因此有点卡住.
直到我更新到最新更新后才出现这些错误.任何帮助是极大的赞赏.

App.xaml.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using COCApp;

using Xamarin.Forms;

namespace COCApp
{
    public partial class App : Application
    {
        public App()
        {
            InitializeComponent();
            MainPage = new NavigationPage(new MainPage());
        }

        protected override void OnStart()
        {
            // Handle when your app starts
        }

        protected override void OnSleep()
        {
            // Handle when your app sleeps
        }

        protected override void OnResume()
        {
            // Handle when your app resumes
        }
    }
}

AppDelegate.cs

using System;
using System.Collections.Generic;
using System.Linq;
using COCApp;
using Foundation;
using UIKit;

namespace COCApp.iOS
{
    // The UIApplicationDelegate for the application. This class is responsible for launching the 
    // User Interface of the application,as well as listening (and optionally responding) to 
    // application events from iOS.
    [Register("AppDelegate")]
    public partial class AppDelegate : global::Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
    {
        //
        // This method is invoked when the application has loaded and is ready to run. In this 
        // method you should instantiate the window,load the UI into it and then make the window
        // visible.
        //
        // You have 17 seconds to return from this method,or iOS will terminate your application.
        //
        public override bool FinishedLaunching(UIApplication app,NSDictionary options)
        {
            global::Xamarin.Forms.Forms.Init();
            LoadApplication(new App());

            return base.FinishedLaunching(app,options);
        }
    }
}