The OnAppearing will not call when first open?

Question

I created a simple xamarin.forms non-shell template

MainPage = new NavigationPage(new MainPage());

and the MainPage set to tabbed page

there are 2 pages in the tabbed page

if I close and re-open the APP the two page's OnAppearing will be called but If I tap the second page it will not be called.

and If I use PushAsync to open a page in the OnAppearing then I close it the two page's OnAppearing will not be called too.

why?

Answer 1

Hello,

Welcome to our Microsoft Q&A platform!

if I close and re-open the APP the two page's OnAppearing will be called but If I tap the second page it will not be called.

From Xamarin.Forms TabbedPage, populate the TabbedPage with a collection of child Page objects, such as a collection of ContentPage objects.

If I use NavigationPage and ContentPage for second Page, I can encounter your probelm.

<TabbedPage  
    x:Class="FormsSample.tabbedpage.TabbedPage4"  
    xmlns="http://xamarin.com/schemas/2014/forms"  
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"  
    xmlns:list="clr-namespace:FormsSample.collectionviewsample">  
    <!--  Pages can be added as references or inline  -->  
    <list:Page1 />  
    <!--<list:Page2 />-->  
    <NavigationPage>  
        <x:Arguments>  
            <list:Page2 />  
        </x:Arguments>  
    </NavigationPage>  
</TabbedPage>  

If I don't use NavigationPage and ContentPage, only first page's OnAppearing will be called when I open app, If I tap the second page, second page's OnAppearing will be called.

<TabbedPage  
    x:Class="FormsSample.tabbedpage.TabbedPage4"  
    xmlns="http://xamarin.com/schemas/2014/forms"  
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"  
    xmlns:list="clr-namespace:FormsSample.collectionviewsample">  
    <!--  Pages can be added as references or inline  -->  
    <list:Page1 />  
    <list:Page2 />  
      
</TabbedPage>  

Best Regards,
Cherry Bu
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