Xamarin Forms Shell GotoAsync - xamarin.forms

I am using the Shell template from VS2019 in a Xamarin Forms app.I have two pages listed in the shell flyout.
<FlyoutItem Title="Home" Icon="icon_about.png">
<ShellContent Route="HomePage" ContentTemplate="{DataTemplate local:HomePage}" />
</FlyoutItem>
<FlyoutItem Title="Logoff time" Icon="icon_about.png">
<ShellContent Route="SecondPage" ContentTemplate="{DataTemplate
local:SecondPage}" />
</FlyoutItem>
Using the hamburger menu I navigate away from the Homepage to another page SecondPage. I have a button on the SecondPage which perform an action and from that action I want to navigate back to the HomePage. When I use this code:
var route = $"{nameof(HomePage)}";
await Shell.Current.GoToAsync(route);
The HomePage shows but there is a back button instead of the hamburger menu. If I tap the hamburger icon the page navigates back to the SecondPage.
How do I navgate from SecondPage to HomePage and show the hamburger icon?

With so little information (not knowing the details of how your navigation is implemented) it's hard to help you. But the first things that come to mind are the following you could try.
Try one of the following for popping the SecondPage and navigating back to:
await Shell.Current.Navigation.PopAsync();
or
await Shell.Current.Navigation.PopModalAsync();
And if you have a navigation bar with a back button that you don't want then try this in the HomePage.xaml
NavigationPage.HasNvaigationBar="False"
or
Shell.NavBarIsVisible="False"

The two
//
before the route will accomplish my aims.This resets the root page apparently so HomePage once again become the root page.
var route = $"//{nameof(HomePage)}"

I have solved this issue in my own project; I wanted this page to show up at the start of the application, using the navigation class to push the screen and then pop it when the user clicks a button. I had the same issue of a back button showing up, instead of the hamburger icon, when moving the user to the HomePage. I hope this helps someone in the future.
Classes are as follows:
public partial class AppShell : Xamarin.Forms.Shell {
public AppShell() {
InitializeComponent();
Routing.RegisterRoute(nameof(ItemDetailPage), typeof(ItemDetailPage));
Routing.RegisterRoute(nameof(NewItemPage), typeof(NewItemPage));
Routing.RegisterRoute(nameof(HomePage), typeof(HomePage));
Routing.RegisterRoute(nameof(NewUserPage), typeof(NewUserPage));
this.Navigation.PushAsync(new NewUserPage());
}
}
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class NewUserPage : ContentPage {
public NewUserPage() {
InitializeComponent();
this.BindingContext = new NewUserViewModel();
Shell.SetNavBarIsVisible(this, false);
}
}
class NewUserViewModel : BaseViewModel {
public NewUserViewModel() {
NewUserClickedCommand = new Command(OnNewUserClicked);
}
public Command NewUserClickedCommand { get; }
private async void OnNewUserClicked() {
await Shell.Current.Navigation.PopAsync();
}
}
And the XAML file for NewUserPage:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="Project.Views.NewUserPage">
<ContentPage.Content>
<StackLayout>
<Label Text="This is a page for new users"
VerticalOptions="CenterAndExpand"
HorizontalOptions="CenterAndExpand" />
<Button Text="Click for New User" BackgroundColor="{StaticResource Primary}" Command="{Binding NewUserClickedCommand}"></Button>
</StackLayout>
</ContentPage.Content>
</ContentPage>

Related

Any ideas why "GoToAsync" doesn't work in AppShell.cs?

Register detail page routes
AppShell.cs
public partial class AppShell : Xamarin.Forms.Shell
{
public AppShell(string message)
{
InitializeComponent();
Routing.RegisterRoute(nameof(ItemDetailPage), typeof(ItemDetailPage));
Routing.RegisterRoute(nameof(NewItemPage), typeof(NewItemPage));
Routing.RegisterRoute("LoginPage", typeof(LoginPage));
if (message != "main") {
int itemid = Int32.Parse(message);
var item = App.Database.GetItemAsyncId(itemid).Result;
var itemValue = new Models.Item
{
Id = item.Id,
Description = item.Description,
Text = item.Text
};
OnItemSelected(itemValue);
}
}
public async void OnItemSelected(Item item)
{
await Shell.Current.GoToAsync("LoginPage");
//Shell.Current.GoToAsync($"{nameof(ItemDetailPage)}?{nameof(ItemDetailViewModel.ItemId)}={item.Id}");
}}
When I launch the application on the emulator, the application should launch the pages:
"AboutPage" - starts;
"LoginPage" - it does not start.
"LoginPage" should load using
Shell.Current.GoToAsync("LoginPage");
The editor does not show errors.
is navigationStack
<FlyoutItem x:Name="ItemsPage" Icon="icon_feed.png">
<ShellContent Route="ItemsPage" ContentTemplate="{DataTemplate local:ItemsPage}" />
</FlyoutItem>
<FlyoutItem x:Name="About" Icon="icon_about.png">
<ShellContent Route="AboutPage" ContentTemplate="{DataTemplate local:AboutPage}" />
</FlyoutItem>
<!-- When the Flyout is visible this will be a menu item you can tie a click behavior to -->
<MenuItem Text="Logout" StyleClass="MenuItemLayoutStyle" Clicked="OnMenuItemClicked">
</MenuItem>
<!--
TabBar lets you define content that won't show up in a flyout menu. When this content is active
the flyout menu won't be available. This is useful for creating areas of the application where
you don't want users to be able to navigate away from. If you would like to navigate to this
content you can do so by calling
await Shell.Current.GoToAsync("//LoginPage");
-->
<TabBar>
<ShellContent Route="LoginPage" ContentTemplate="{DataTemplate local:LoginPage}" />
</TabBar>
Does your method get called?
What is the value of the message variable? Check if the if (message != "main") is true sometimes
It will only happen on the constructor.
[Edit]
To navigate a page of a Shell inside the constructor, you will have to replace "Shell.Current.GoToAsync('LoginPage')" with "this.GoToAsync('LoginPage')"
At the moment of the instance, the created Shell is not the "Current" shell of the application

How to display two text boxes as pop up using DisplayPromptAsync method in xamarin?

When I use -
string result = await DisplayPromptAsync("Question 1", "What's your name?");
It shows only one textbox in the pop-up. But how to display two or more textboxes in the pop-up?
Any help would be greatly appreciated.
As IvanIčin said that you can use Rg.Plugins.Popup to create custom popup.
Firstly, install Rg.Plugins.Popup bu nuget package..., then creating popup page
<pages:PopupPage
x:Class="FormsSample.popup.popup2"
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:pages="clr-namespace:Rg.Plugins.Popup.Pages;assembly=Rg.Plugins.Popup">
<pages:PopupPage.Content>
<StackLayout
Padding="20,0"
BackgroundColor="CadetBlue"
HorizontalOptions="FillAndExpand"
VerticalOptions="Center">
<Label Text="Question 1" />
<Label Text="this is one question!" />
<Entry />
<Entry />
<Button
x:Name="btnsub"
Clicked="btnsub_Clicked"
Text="subit" />
</StackLayout>
</pages:PopupPage.Content>
</pages:PopupPage>
public partial class popup2 : PopupPage
{
public popup2()
{
InitializeComponent();
}
private void btnsub_Clicked(object sender, EventArgs e)
{
}
}
To call this Popup Page from contentpage button.click event.
private async void btnPopupButton_Clicked(object sender, EventArgs e)
{
await PopupNavigation.Instance.PushAsync(new popup2());
}
You can see the screenshot:
You can't as it is not intended to. You can create a custom pop-up either by using some pop-up plug-in or by creating your custom code based on the native prompts (similar to what Xamarin.Forms do).
Just for the record having one input field is very generous from Xamarin as the native Android or iOS developers don't have such a prompt with the input field out of the box (though it isn't too hard to create it but still it goes much beyond one line of code).

XamarinForms Shell navigation with TabBar items of previous page

I need to create a "detail" page that when I clicked from my "master" page, on some button, it redirects me to that "detail" page with navigation bar which has back button.
Code for this is as follows:
protected async Task GoToPage(string route)
{
await Shell.Current.GoToAsync(route);
}
Question is: how to preserve downtab from my previous master page, to show as well as on my detail page?
design is look like this:
https://i.imgur.com/tBqHhH8.png
I only have navigation bar.
In my AppShell.xaml I defined TabBar section for my "master" page ("master" page is first in my tabbar menu).
Should I create separate TabBar for my "detail" page and somehow to insert navigation bar?
You can put your Page to the MenuItem tab.
<MenuItem Text="About"
IconImageSource="info.png"
Command="{Binding AboutPageCommand}" />
Background code.
public ICommand AboutPageCommand => new Command(async () => await NavigateToAboytPageAsync());
async Task NavigateToAboytPageAsync()
{
await Shell.Current.GoToAsync($"aboutPage");
Shell.Current.FlyoutIsPresented = false;
}
Register the page in the App.xaml.cs
Routing.RegisterRoute("aboutPage", typeof(AboutPage));
There is a property called IsTabStop you can set in the Tab tag which can preserve downtab from your previous master page:
IsTabStop, of type bool, indicates whether a Tab is included in tab
navigation. Its default value is true, and when its value is false the
Tab is ignored by the tab-navigation infrastructure, irrespective if a
TabIndex is set.
You can set it to false at specific tab to keep downtab at that tab.
Code example:
<!-- Your Pages -->
<TabBar>
<Tab Title="Master" Icon="tab_feed.png" IsTabStop="False">
<ShellContent ContentTemplate="{DataTemplate local:ItemsPage}" />
</Tab>
<Tab Title="About" Icon="tab_about.png" >
<ShellContent ContentTemplate="{DataTemplate local:AboutPage}" />
</Tab>
</TabBar>
Here is the document: shell/tabs

Master Detail breaks parameters?

I don't need a MasterDetail until I've navigated through two regular ContentPages first, where I collect information that the MasterDetail will need. The ContentPages make use of the INavigationParameters sent to OnNavigatedTo and OnNavigatedFrom for that collected information.
The the SecondPage viewmodel handles a button command wherein the handler calls the MasterDetail:
NavigationService.NavigateAsync("CompareSelectionsMasterDetail/CompareSelectionsNavigationPage/RangeCircle",
parameters);
Sure enough, the RangeCircleViewModel.OnNavigatedTo receives the parameters. However, when I go back (like with the Android back button), its OnNavigatedFrom is not called, thereby sending null parameters back leaving my ContentPages with no idea what their state was.
The viewmodel for CompareSelectionMasterDetail doesn't do anything and the viewmodel for CompareSelectionsNavigationPage just does this:
public class CompareSelectionsNavigationPage : NavigationPage, INavigationPageOptions
{
public bool ClearNavigationStackOnNavigation => false;
}
I'm not sure what it means to have a NavigationPage in the MasterDetailPage XAML and the separate CompareSelectionsNavigationPage that I call with Prism but if I remove the XAML one, the RangeCircle page doesn't render. If I only have the XAML one and change the Prism navigation to CompareSelectionsMasterDetail/NavigationPage/RangeCircle then I get the same behavior as using both NavigationPages.
My MasterDetail XAML is simple.
> <MasterDetailPage.Master>
> <NavigationPage Title="Required Foo" Icon="hamburger_icon.png">
> <x:Arguments>
> <ContentPage Title="Menu">
> <StackLayout Padding="40">
> <!-- TODO: // Update the Layout and add some real menu items -->
> <Label Text="Hello John"/>
> <Button Text="Range Circle" Command="{Binding NavigateToRangeCircleCommand}" CommandParameter="ViewA" />
> </StackLayout>
> </ContentPage>
> </x:Arguments>
> </NavigationPage> </MasterDetailPage.Master>
Every example I can find of Master Detail (especially with Prism) starts off the app with Master Detail page. I'm not sure if my usage is what breaks OnNavigatedFrom? (Basically ContentPage(Page1)->ContentPage(Page2)->MasterDetail->NavigationPage->NavigationPage->ContentPage(RangeCircle))
The individual ContentPages don't have a problem calling OnNavigatedFrom.

Back button missing on NavigationPage

I'm using Prism.Forms 6.3 in a Xamarin.Forms 2.3.4.247 project. I'm having a hard time tracking why the back arrow button isn't visible when I navigate to a details page within a Master/Detail setup.
I can navigate to the Pages just fine, but the back-button never shows up. Instead, the hamburger menu icon is always visible. This is my "Master" page.
<?xml version="1.0" encoding="utf-8" ?>
<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:FloatSink.Apps.Mobile.Views.ValueConverters"
xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="FloatSink.Apps.Mobile.Views.MainPage"
BackgroundColor="Blue">
<MasterDetailPage.Master>
<ContentPage Title="Menu">
<StackLayout Padding="40">
<Label Text="Hello" />
<Button Text="Feed" Command="{Binding NavigateCommand}" CommandParameter="NavigationPage/FeedPage" />
<Button Text="Options" Command="{Binding NavigateCommand}" CommandParameter="NavigationPage/OptionsPage" />
</StackLayout>
</ContentPage>
</MasterDetailPage.Master>
</MasterDetailPage>
This is two of my Detail pages.
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="FloatSink.Apps.Mobile.Views.FeedPage">
<Label Text="Hello from Feed Page!" />
</ContentPage>
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="FloatSink.Apps.Mobile.Views.OptionsPage">
<Label Text="Hello from Options Page!" />
</ContentPage>
I navigate to it using the CommandParameter specified in my Master page, using the navigation service in the MainPageViewModel.
private void NavigateToPage(string uri)
{
this.navigationService.NavigateAsync(uri);
}
I've setup my NavigationPage like this during the startup of the app so I land on the FeedPage first, then I can navigate to the OptionsPage.
public class App : PrismApplication
{
public App(IPlatformInitializer dependencyRegister) : base(dependencyRegister) { }
protected override void OnInitialized()
{
base.NavigationService.NavigateAsync("MainPage/NavigationPage");
}
protected override void RegisterTypes()
{
var builder = new ContainerBuilder();
builder.RegisterModule<NavigationRegistration>();
builder.RegisterModule<ServicesRegistration>();
base.Container.RegisterTypeForNavigation<NavigationPage>();
// This is deprecated but we have to wait for Prism.Autofac to update itself
builder.Update(base.Container);
}
}
The DI registrations associated with navigation are done in this module:
internal class NavigationRegistration : Module
{
/// <summary>
/// Load the navigation related types into the given builder.
/// </summary>
/// <param name="builder">Container Builder that will be turned into the final IOC Container</param>
protected override void Load(ContainerBuilder builder)
{
// Register the NavigationPage in Xamarin with the Prism Navigation system.
//builder.RegisterType<NavigationPage>().AsSelf();
//PageNavigationRegistry.Register(nameof(NavigationPage), typeof(NavigationPage));
// Get all of the Types that represent a View in our assembly for DI and navigation registration
// If start-up time ever becomes an issue, we can replace this assembly scan with explicit registrations.
Type[] viewTypes = base.ThisAssembly.GetTypes().Where(type => type.IsAssignableTo<Page>()).ToArray();
// Iterate over each discovered View Type and register it with the navigation system and DI container.
for(int index = 0; index < viewTypes.Length; index++)
{
Type viewType = viewTypes[index];
builder.RegisterType(viewType).Named<Page>(viewType.Name);
// If we ever need to disconnect a view name from its Type name, we can do so here.
// We would build a custom attribute to decorate the view with, pull the attribute from the Type
// and register the Type with the attribute value.
PageNavigationRegistry.Register(viewType.Name, viewType);
}
}
}
Again I can each one of my detail pages without problem, the hamburger menu exists and I can open the Master page to view my buttons used for navigating. I just can't navigate backwards once I'm there. Is that something I'm supposed to wire up myself?
I'm not sure I'm reading your question right but it sounds like this is normal behavior. In my (short) experience with XF/Prism, every navigation from the master is a beginning of the stack. If you were to add another page, e.g. from Master->PageA->PageB, I would expect Page A to have the hamburger menu but going to PageB would give you the back arrow.
For using NavigationPage inside uri you should register it for navigation in the App.xaml.cs:
protected override void RegisterTypes()
{
// your registrations
Container.RegisterTypeForNavigation<NavigationPage>();
}
I most cases it is the reason.
To Navigate To Master Page
"/MasterPage/NavigationPage/ViewA"
To Navigate out of Master Page from ViewA and with back button
"ViewB"
You need to start your app with MainPage = new NavigationPage(new StartPage()); That is how it is solved in normal situation. So maybe try to register your MainPage wrapped in a NavigationPage.

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