Xamarin搜索栏未显示

Question

Is there any reason why a Xamarin.Forms search bar wouldn't show on Android (currently running Android 7.0). I read that it might be a good idea to do a HeightRequest but even after trying that, the search bar still doesn't show up. Here's what I have in my xaml to initialize the search bar:

<SearchBar x:Name="searchBarList" Placeholder="Search" HeightRequest="42" Opacity="1"/>

Any idea how to move forward?

UPDATE: The whole layout looks like this:

<?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="SalApp.views.MainList" BackgroundColor="LightGray" NavigationPage.HasNavigationBar="False">
<ContentPage.ToolbarItems>
    <ToolbarItem Icon="shopping_cart_icon.png" 
            Priority="0" Order="Primary" />
</ContentPage.ToolbarItems>
<SearchBar x:Name="searchBarList"
                    Placeholder="Search"
                    HeightRequest="42"
           Opacity="1"/>
<ListView x:Name="listView" Opacity="0" SeparatorColor="AntiqueWhite" RowHeight="80" ItemSelected="listView_ItemSelected" IsPullToRefreshEnabled="True"/>

But it's only set up like this currently in order to see the search bar but it's still not visible

Answer 1

Your problem is that you have more than one View in the root of your ContentPage .

Group your View s under a parent control, an example:

<?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="SalApp.views.MainList" BackgroundColor="LightGray" NavigationPage.HasNavigationBar="False">
<ContentPage.ToolbarItems>
    <ToolbarItem Icon="shopping_cart_icon.png" 
            Priority="0" Order="Primary" />
</ContentPage.ToolbarItems>
    <StackLayout>
        <SearchBar x:Name="searchBarList"
                            Placeholder="Search"
                            HeightRequest="42"
                    Opacity="1"/>
        <ListView x:Name="listView" Opacity="0" SeparatorColor="AntiqueWhite" RowHeight="80" ItemSelected="listView_ItemSelected" IsPullToRefreshEnabled="True"/>
    </StackLayout>
</ContentPage>

Answer 2

In case that you want a more general way to resolve this and not adding manually a HeightRequest you can implement a SearchBarRenderer

using Android.OS;
using AppTTM_AVI.Droid;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(SearchBar), typeof(CustomSearchBarRenderer))]
namespace App.Droid
{
    /// <summary>
    /// Workaround for searchBar not appearing on Android >= 7
    /// </summary>
    public class CustomSearchBarRenderer : SearchBarRenderer
    {
        public CustomSearchBarRenderer()
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<SearchBar> e)
        {
            base.OnElementChanged(e);

            if (e.OldElement != null || Element == null)
            {
                return;
            }

            if (Build.VERSION.SdkInt >= BuildVersionCodes.N)
            {
                Element.HeightRequest = 42;
            }
        }
    }
}

Source: https://forums.xamarin.com/discussion/comment/296772/#Comment_296772

Answer 3

Android 7.0 and 7.1 Search bar appears first time after installation once I logout or changes the orientation to landscape mode its gone, Have implemented this code as well.

protected override void OnElementChanged(ElementChangedEventArgs<SearchBar> e)
            {
                base.OnElementChanged(e);

                if (e.OldElement != null || Element == null)
                    return;

                if(Build.VERSION.SdkInt >= BuildVersionCodes.N)
                     Element.HeightRequest = 40;
            }