Question

因为我是Xamarin的新手，所以我真的不知道如何在页面之间切换。所以我指的是互联网并找到了一些解决方案。但是有一些错误。任何人都可以帮忙解决这个问题吗？这是我在app.cs文件中的代码。我对我不确定的代码添加了注释。当我点击btn1时，触发了一个名为“ios全局不支持pushAsync”的错误。

using System;

使用Xamarin.Forms;

命名空间我的 { 公共类App：应用程序 { 公共应用（） {

        // 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

导航是VisualElement的属性。 Button.Clicked的所有代码都在App类的构造函数中（它是Application的子类），它没有＆＃34; Navigation＆＃34;属性。在您的情况下，您可以使用MainPage.Navigation（因为MainPage是一个页面，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（..）。要解决此问题，您应该将ContentPage包装到导航页面中，如下所示：

    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);

顺便说一下，this arcticle将帮助您了解正在发生的事情。

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
        }
    }
}

我希望这能正常运作。

Answer 2

getLogger是Page的属性。你必须打电话给

Navigation

我需要在xamarin.Forms.app上从一个页面导航到另一个页面

2 个答案: