I am trying to add a tabbed page as shown in the xamarin documentation but I keep getting the following error, System.NullReferenceException "Object reference not set to an instance of an object." Do I need to declare a new object for each page or is this done automatically when using xaml?
Here is my StackTrace,
at Xamarin.Forms.Platform.Android.AppCompat.Platform.LayoutRootPage(Xamarin.Forms.P age page, Int32 width, Int32 height) [0x0005d] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Platform.Android\AppCompat\Plat form.cs:279
at Xamarin.Forms.Platform.Android.AppCompat.Platform.Xamarin.Forms.Platform.Android.IPlatformLayout.OnLayout (Boolean changed, Int32 l, Int32 t, Int32 r, Int32 b) [0x00003] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Platform.Android\AppCompat\Platform.cs:196
at Xamarin.Forms.Platform.Android.PlatformRenderer.OnLayout (Boolean changed, Int32 l, Int32 t, Int32 r, Int32 b) [0x0000e] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Platform.Android\PlatformRenderer.cs:73
at Android.Views.ViewGroup.n_OnLayout_ZIIII (IntPtr jnienv, IntPtr native__this, Boolean changed, Int32 l, Int32 t, Int32 r, Int32 b) [0x00009] in /Users/builder/data/lanes/3415/7db2aac3/source/monodroid/src/Mono.Android/platforms/android-23/src/generated/Android.Views.ViewGroup.cs:3427
at (wrapper dynamic-method) System.Object:d59f31f1-b9b6-40ea-9254-a422fe409750 (intptr,intptr,bool,int,int,int,int)
Here is my code,
using Xamarin.Forms;
namespace BSi.Mobile.Events.Views
{
public partial class MainMasterDetailPage : MasterDetailPage
{
public MainMasterDetailPage()
{
InitializeComponent();
}
}
}
<?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:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
xmlns:local="clr-namespace:BSi.Mobile.Events.Views;assembly=BSi.Mobile.Events"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="BSi.Mobile.Events.Views.MainMasterDetailPage">
<MasterDetailPage.Master>
<ContentPage Title="Default" Padding="10">
<StackLayout>
<Button Text="Home" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\MainPage"/>
<Button Text="Event Schedule" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\EventPage"/>
<Button Text="Floor Plan" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\FloorPlanPage"/>
<Button Text="Sponsor/Media Partners" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\SponsorsPage"/>
<Button Text="Where To Eat" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\FoodNearbyPage"/>
</StackLayout>
</ContentPage>
</MasterDetailPage.Master>
<MasterDetailPage.Detail>
<TabbedPage>
<TabbedPage.Children>
<local:MainPage Title="Info" Icon="http://icons.iconarchive.com/icons/graphicloads/100-flat/256/home-icon.png"/>
<local:EventPage Title="Sessions" Icon="http://icons.iconarchive.com/icons/graphicloads/100-flat/256/home-icon.png"/>
<local:SpeakersPage Title="Speakers" Icon="http://icons.iconarchive.com/icons/graphicloads/100-flat/256/home-icon.png"/>
<local:ExhibitsPage Title="Exhibits" Icon="http://icons.iconarchive.com/icons/graphicloads/100-flat/256/home-icon.png"/>
</TabbedPage.Children>
</TabbedPage>
</MasterDetailPage.Detail>
</MasterDetailPage>
UPDATE:
I made some changes as suggested by SushiHangover, I now recieve no errors but my tabbed menu is not appearing.
The answer was to use command parameter that is relative to the pages to be displayed in the tabbed 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:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="BSi.Mobile.Events.Views.MainMasterDetailPage">
<MasterDetailPage.Master>
<ContentPage Title="Default">
<StackLayout>
<StackLayout BackgroundColor="{StaticResource iconGray}" Padding="15" HeightRequest="100">
<Image Source="canfitpro_logo2" HeightRequest="60" HorizontalOptions="Start" VerticalOptions="EndAndExpand" />
</StackLayout>
<TableView Intent="Form" HasUnevenRows="True">
<TableRoot>
<TableSection Title="Vancouver Fitness Expo">
<ViewCell>
<StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="EventTabbedPage/NavigationPage/MainPage"/>
</StackLayout.GestureRecognizers>
<Image Source="icon_home_circle" HeightRequest="40"/>
<Label Text="Home" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/>
</StackLayout>
</ViewCell>
<ViewCell>
<StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="EventTabbedPage/NavigationEventPage"/>
</StackLayout.GestureRecognizers>
<Image Source="icon_sessions_circle" HeightRequest="40"/>
<Label Text="Sessions" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/>
</StackLayout>
</ViewCell>
</TableSection>
<TableSection Title="Resources">
<ViewCell>
<StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage/FloorPlanPage"/>
</StackLayout.GestureRecognizers>
<Image Source="icon_floormap_circle" HeightRequest="40"/>
<Label Text="Floor Plan" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/>
</StackLayout>
</ViewCell>
<ViewCell>
<StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage/SponsorsPage"/>
</StackLayout.GestureRecognizers>
<Image Source="icon_partners_circle" HeightRequest="40"/>
<Label Text="Sponsor / Media Partners" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/>
</StackLayout>
</ViewCell>
<ViewCell>
<StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage/FoodNearbyPage"/>
</StackLayout.GestureRecognizers>
<Image Source="icon_restaurant_circle" HeightRequest="40"/>
<Label Text="Where To Eat" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/>
</StackLayout>
</ViewCell>
</TableSection>
</TableRoot>
</TableView>
</StackLayout>
</ContentPage>
</MasterDetailPage.Master>
</MasterDetailPage>