我需要从一个页面导航到另一个页面上xamarin.Forms.app

Question

因为我是Xamarin新手，我真的不知道如何在页面之间切换。所以我提到互联网并找到了一些解决方案。但有一些错误。任何人都可以帮助解决这个问题？这是我在app.cs文件中的代码。我对代码进行评论，我不确定。当我点击btn1时，触发了一个名为“pushAsync在ios上不支持全局”的错误。使用Xamarin.Forms

using System; 

;

命名空间矿山 { 公共类应用：应用 { 公共应用程序（）{

 // The root page of your application 


     Button btn1 = new Button(); 
     Button btn2 = new Button(); 
     Button btn3 = new Button(); 
     btn1.Text= "Farmer"; 
     btn2.Text= "Advisor"; 
     btn3.Text= "Supplier"; 

     MainPage = new ContentPage { 
      Content = new StackLayout { 
       VerticalOptions = LayoutOptions.Center, 
       Children = { 
        new Label { 
         XAlign = TextAlignment.Center, 
         Text = "Welcome to Rice Growing Advisor!" 
          //App.Navigation.PushAsync(new MyCustomContentPage()); 
          //App.Navigation.PushAsync (new MainPage()); 
        }, btn1,btn2,btn3 
       } 
      } 



     }; 
     //var np = new NavigationPage(new MainPage()); 
     //MainPage=np; 
     //MainPage = new NavigationPage (MainPage); 
     //var rootPage = new NavigationPage(MainPage); 



     btn1.Clicked += async (sender, e) => { 
      //MainPage= new NavigationPage(new MainPage()); 
      //MainPage = np; 

      await MainPage.Navigation.PushAsync(new NavigationPage()); 
      MainPage.Navigation.RemovePage(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 
    } 
} 

}

Answer 1

导航属性的VisualElement。 Button.Clicked的所有代码都在App类（它是Application的子类）的构造函数中，它没有“Navigation”属性。 你的情况你可以使用MainPage.Navigation（因为MainPage是一个Page和Page是一个VisualElement）。但还有一个问题：您的MainPage不是NavigationPage，因此您无法执行PushAsync（..）。要解决这个问题，你应该只是包装ContentPage进入导航页面是这样的：

var page = new ContentPage { 
     Content = new StackLayout { 
      VerticalOptions = LayoutOptions.Center, 
      Children = { 
       new Label { 
        XAlign = TextAlignment.Center, 
        Text = "Welcome to Rice Growing Advisor!" 
         //App.Navigation.PushAsync(new MyCustomContentPage()); 
         //App.Navigation.PushAsync (new MainPage()); 
       }, btn1,btn2,btn3 
      } 
     } 
    }; 

    MainPage = new NavigationPage(page); 

顺便说一句，this arcticle将帮助ü明白是怎么回事。

编辑：

using System; 
using Xamarin.Forms; 

namespace test 
{ 
    public class App : Application 
    { 
     public App() 
     { 
      // The root page of your application 

      // set up properties via object initializer for clarity 
      Button btn1 = new Button {Text = "Farmer"}; 
      Button btn2 = new Button {Text = "Advisor"}; 
      Button btn3 = new Button {Text = "Supplier"}; 

      var page = new ContentPage { 
       Content = new StackLayout { 
        VerticalOptions = LayoutOptions.Center, 
        Children = { 
         new Label { 
          // XAlign is obsolete, use HorizontalTextAlignment instead 
          HorizontalTextAlignment = TextAlignment.Center, 
          Text = "Welcome to Rice Growing Advisor!" 
         }, btn1,btn2,btn3 
        } 
       } 
      }; 

      // wrap our page into NavigationPage 
      // if we dont do that, we'll get "PushAsync is not supported globally on iOS" exception 
      MainPage = new NavigationPage(page); 

      btn1.Clicked += async (sender, e) => { 
       var secondPage = new ContentPage 
       { 
        Content = new Label 
        { 
         Text = "Click \"BACK\" to navigate backward", 
         HorizontalTextAlignment = TextAlignment.Center, 
         VerticalTextAlignment = TextAlignment.Center 
        } 
       }; 
       secondPage.ToolbarItems.Add(new ToolbarItem("BACK", null, async() => { await secondPage.Navigation.PopAsync();})); 

       await MainPage.Navigation.PushAsync(secondPage); 
      }; 
     } 

     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 
     } 
    } 
} 

我希望这个工作正常。

Answer 2

Navigation是页面的一个属性。你必须打电话像

await MainPage.Navigation.PushAsync(new ExamplePage(1));