我需要從一個頁面導航到另一個頁面上xamarin.Forms.app

Question

因爲我是Xamarin新手，我真的不知道如何在頁面之間切換。所以我提到互聯網並找到了一些解決方案。但有一些錯誤。任何人都可以幫助解決這個問題？這是我在app.cs文件中的代碼。我對代碼進行評論，我不確定。當我點擊btn1時，觸發了一個名爲「pushAsync在ios上不支持全局」的錯誤。使用Xamarin.Forms

using System; 

;

命名空間礦山 { 公共類應用：應用 { 公共應用程序（）{

 // 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

導航屬性的VisualElement。 Button.Clicked的所有代碼都在App類（它是Application的子類）的構造函數中，它沒有「Navigation」屬性。 你的情況你可以使用MainPage.Navigation（因爲MainPage是一個Page和Page是一個VisualElement）。但還有一個問題：您的MainPage不是NavigationPage，因此您無法執行PushAsync（..）。要解決這個問題，你應該只是包裝ContentPage進入導航頁面是這樣的：

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); 

順便說一句，this arcticle將幫助ü明白是怎麼回事。

編輯：

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 
     } 
    } 
} 

我希望這個工作正常。

Answer 2

Navigation是頁面的一個屬性。你必須打電話像

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