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Hi,
I was wondering if someone of you got a tip for me regarding the following problem:
I've a xaml view with the following content:
xmlversion="1.0"encoding="UTF-8"?>
<ContentView
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="TPApp.gui.views.category.CategoryHomeListView"
xmlns:carousel="clr-namespace:Syncfusion.SfCarousel.XForms;assembly=Syncfusion.SfCarousel.XForms">
<GridRowSpacing="0"ColumnSpacing="0">
<Grid.RowDefinitions>
<RowDefinitionHeight="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinitionWidth="*"/>
</Grid.ColumnDefinitions>
<Grid.Resources>
<ResourceDictionary>
<DataTemplatex:Key="tpProductItemTemplate">
<GridRowSpacing="0"ColumnSpacing="0"VerticalOptions="Center"HorizontalOptions="Center">
<Grid.RowDefinitions>
<RowDefinitionHeight="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinitionWidth="*"/>
</Grid.ColumnDefinitions>
<ImageSource="{BindingsImageUrl}"VerticalOptions="Center"HorizontalOptions="Center"Grid.Row="0"
Grid.Column="0"/>
</Grid>
</DataTemplate>
</ResourceDictionary>
</Grid.Resources>
<carousel:SfCarouselx:Name="tpProductCarousel"HeightRequest="400"WidthRequest="400"Grid.Row="0"
Grid.Column="0"ItemTemplate="{StaticResourcetpProductItemTemplate}"/>
</Grid>
</ContentView>
I'm adding the content via the following code in the .cs file:
publicCategoryHomeListView()
{
InitializeComponent();
tpProductCarousel.SetBinding(Syncfusion.SfCarousel.XForms.SfCarousel.DataSourceProperty,"aProducts");
}
The whole project is compiling fine. But as soon as I'm starting the program, I get the following exception:
System.NullReferenceException: Object reference not set to an instance of an object
at Syncfusion.SfCarousel.XForms.iOS.SfCarouselMapping.Convert (Xamarin.Forms.View source, Xamarin.Forms.VisualElement valid) [0x0002f] in <7b928492986e4ddaabcc39b707c50172>:0
at Syncfusion.SfCarousel.XForms.iOS.SfCarouselMapping.ConvertFormsToNative (Xamarin.Forms.DataTemplate view, System.nint index, CoreGraphics.CGRect size, Syncfusion.SfCarousel.XForms.SfCarousel formsCarousel) [0x0002a] in <7b928492986e4ddaabcc39b707c50172>:0
at Syncfusion.SfCarousel.XForms.iOS.SfCarouselMapping.OnCarouselPropertiesChanged (System.String propertyName, Syncfusion.SfCarousel.XForms.SfCarousel formsCarousel, Syncfusion.SfCarousel.iOS.SFCarousel nativeCarousel) [0x00379] in <7b928492986e4ddaabcc39b707c50172>:0
at Syncfusion.SfCarousel.XForms.iOS.SfCarouselRenderer.OnElementChanged (Xamarin.Forms.Platform.iOS.ElementChangedEventArgs`1[TElement] e) [0x000a3] in <7b928492986e4ddaabcc39b707c50172>:0
......
Does anyone of you know, why it accesses an empty object? The carousel has been added in the xaml and should have been initialized by calling
InitializeComponent(); ?
Thank you very much for your help.
Alex
Hi Rathanakumar,
Thanks for the example code you attached to your reply.. The ViewModel Binding is one level above. First I thought you're right and I forgot the Context Binding. But I'm doing this outside of CategoryHomeListView like
CategoryHomeListView oObj = new CategoryHomeListView();
oObj.BindingContext = oCatObj;
oCatObj has the member "aProducts" which I use later for binding the item source.
The programm still doesn't work. I'll try some other things. I case you've got another tipp, I'd be happy if you could post it here.
Thank you very much for yor help!
Alex
Hi,
ok.. I tried a little bit more and think the solution comes closer.
I did now the following:
The XAML:
<?xml version="1.0" encoding="UTF-8"?>
<ContentView
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="xyz.gui.views.category.CategoryHomeListView"
xmlns:carousel="clr-namespace:Syncfusion.SfCarousel.XForms;assembly=Syncfusion.SfCarousel.XForms" >
<StackLayout>
<carousel:SfCarousel x:Name="tpProductCarousel" HeightRequest="400" WidthRequest="400" BackgroundColor="Aqua" Margin="20" Grid.Row="0"
Grid.Column="0" />
<Label x:Name="testlabel" />
</StackLayout>
</ContentView>
And the source code:
using System;
using System.Collections.Generic;
using Xamarin.Forms;
namespace xyz.gui.views.category
{
public partial class CategoryHomeListView : ContentView
{
public CategoryHomeListView(webint.entity.category.CategoryHome oCategory)
{
InitializeComponent();
this.BindingContext = oCategory;
testlabel.SetBinding(Label.TextProperty, "sName");
/* Syncfusion.SfCarousel.XForms.SfCarouselItem carouselItem1 = new Syncfusion.SfCarousel.XForms.SfCarouselItem();
Image img = new Image();
img.Source = ImageSource.FromUri(new Uri("http://cerealkillerz.org/wp-content/uploads/2015/12/yvqylz3c0ywhkpt1g8of.jpgimage2.png"));
img.Aspect = Aspect.AspectFit;
img.VerticalOptions = LayoutOptions.Center;
img.HeightRequest = 400;
img.WidthRequest = 400;
carouselItem1.ItemContent = img;
tpProductCarousel.ItemsSource.Add(carouselItem1);
Syncfusion.SfCarousel.XForms.SfCarouselItem carouselItem = new Syncfusion.SfCarousel.XForms.SfCarouselItem();
Label lbl = new Label();
lbl.Text = " Item No: 1 ";
lbl.BackgroundColor = Color.Gray;
lbl.FontSize = 25;
lbl.VerticalTextAlignment = TextAlignment.Center;
carouselItem.ItemContent = lbl;
tpProductCarousel.ItemsSource.Add(carouselItem); */
}
}
}
And now the strange thing:
If I dont add any of the items above to the SfCarousel (the part in the code which I commented) it works like charm. I see the list of my categories with the light blue SfCarousel. But as soon as I try to add the items as you see it above (e.g. as soon as I remove the /* and */), it crashed at runtime. The message is the following:
Caught Exception 1: System.NullReferenceException: Object reference not set to an instance of an object
at Syncfusion.SfCarousel.XForms.iOS.SfCarouselRenderer.Convert
(Xamarin.Forms.View source, Xamarin.Forms.VisualElement valid) [0x0002f]
in <7b928492986e4ddaabcc39b707c50172>:0
at
Syncfusion.SfCarousel.XForms.iOS.SfCarouselRenderer.ConvertFormsToNative
(Xamarin.Forms.View view, CoreGraphics.CGRect size,
Syncfusion.SfCarousel.XForms.SfCarousel formsCarousel) [0x00007] in
<7b928492986e4ddaabcc39b707c50172>:0
at
Syncfusion.SfCarousel.XForms.iOS.SfCarouselItemMapping.OnCarouselItemPropertiesChanged
(System.String propertyName,
Syncfusion.SfCarousel.XForms.SfCarouselItem formsItem,
Syncfusion.SfCarousel.iOS.SFCarouselItem nativeItem) [0x0004a] in
<7b928492986e4ddaabcc39b707c50172>:0
at
Syncfusion.SfCarousel.XForms.iOS.SfCarouselItemMapping.GetNativeItem
(Syncfusion.SfCarousel.XForms.SfCarouselItem item,
Syncfusion.SfCarousel.XForms.SfCarousel carousel) [0x0002f] in
<7b928492986e4ddaabcc39b707c50172>:0
at
Syncfusion.SfCarousel.XForms.iOS.SfCarouselMapping.OnCarouselPropertiesChanged
(System.String propertyName, Syncfusion.SfCarousel.XForms.SfCarousel
formsCarousel, Syncfusion.SfCarousel.iOS.SFCarousel nativeCarousel)
[0x0005b] in <7b928492986e4ddaabcc39b707c50172>:0
at
Syncfusion.SfCarousel.XForms.iOS.SfCarouselRenderer.OnElementChanged
(Xamarin.Forms.Platform.iOS.ElementChangedEventArgs`1[TElement] e)
[0x000a3] in <7b928492986e4ddaabcc39b707c50172>:0
I'm pretty sure that the more complex styling problem will be solved as soon as I get this to work.
Cloud you have another look to the source code?
Thank you very much.
Is it possible that my Xamarin Forms Version causes the issues?
Xamarin Studio Community
Version 6.3 (build 864)
Installation UUID: xyz
Runtime:
Mono 5.2.0.179 (2017-04/4498dc4) (64-bit)
GTK+ 2.24.23 (Raleigh theme)
Package version: 502000179
NuGet
Version: 3.5.0.0
Xamarin.Profiler
'/Applications/Xamarin Profiler.app' not found
Xamarin.Android
Version: 7.4.0.2 (Xamarin Studio Community)
Android SDK: /Users/xyz/Library/Developer/Xamarin/android-sdk-macosx
Unterstützte Android-Versionen:
6.0 (API-Ebene 23)
7.1 (API-Ebene 25)
Version der SDK-Tools: 25.2.5
Version der SDK-Plattformtools: 25.0.3
Version der SDK-Buildtools: 23.0.2
Java SDK: /usr
java version "1.7.0_71"
Java(TM) SE Runtime Environment (build 1.7.0_71-b14)
Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode)
Android Designer EPL-Code ist hier verfügbar:
https://github.com/xamarin/AndroidDesigner.EPL
Apple Developer Tools
Xcode 8.3.3 (12175.1)
Build 8E3004b
Xamarin Inspector
Not Installed
Xamarin.Mac
Version: 3.6.0.4 (Xamarin Studio Community)
Xamarin.iOS
Version: 10.12.0.5 (Xamarin Studio Community)
Hash: 104e7b43
Branch: d15-3
Build date: 2017-06-08 14:59:48-0400
Build Information
Release ID: 603000864
Git revision: 6c2f6737278ccc3e81e12276d49c0d92f975f189
Build date: 2017-04-24 11:26:01-04
Xamarin addins: d8d46e577d8507c35260ce9d73df3c33415bb214
Build lane: monodevelop-lion-d15-1
Operating System
Mac OS X 10.12.5
Darwin xyz-Mac-mini.local 16.6.0 Darwin Kernel Version 16.6.0
Fri Apr 14 16:21:16 PDT 2017
root:xnu-3789.60.24~6/RELEASE_X86_64 x86_64
Hi,
Thanks for your answer. I opened the project and tried to compile it. I get the message "/Users/.../Documents/Xamarin/CarouselTesting/iOS/AppDelegate.cs(29,29): Error CS0234: The type or namespace name 'XForms' does not exist in the namespace 'Syncfusion.SfCarousel' (are you missing an assembly reference?) (CS0234) (CarouselTesting.iOS)"
Do you know how I can fix this error? I added the package Syncfusion.Xamarin.SfCarousel.IOS
Thank you very much for your help.
Alex
Hi,
ok - I fixed the problem with adding the Syncfusion.Xamarin.SfCarousel package to the project.
The testproject works fine. I'll try to reproduce the error tomorrow.
Thanks again.
Alex
Hi,
ok, I'm honest, this issue is driving me mad.. ;) The example you attached as .zip file is working fine. I was trying again different settings in my category view class and tested finally for 4 hours on the ContentPage class. The problem has to be somewhere in the Carousel plugin, because the data is showing fine in a ListView.
This version crashes with "Object reference not set to an instance of an object" at " at Syncfusion.SfCarousel.XForms.iOS.SfCarouselMapping.OnCarouselPropertiesChanged (System.String propertyName, Syncfusion.SfCarousel.XForms.SfCarousel formsCarousel, Syncfusion.SfCarousel.iOS.SFCarousel nativeCarousel) [0x00029] in <7b928492986e4ddaabcc39b707c50172>:0
at Syncfusion.SfCarousel.XForms.iOS.SfCarouselRenderer.OnElementChanged (Xamarin.Forms.Platform.iOS.ElementChangedEventArgs`1[TElement] e) [0x000a3] in <7b928492986e4ddaabcc39b707c50172>:0
at Xamarin.Forms.Platform.iOS.VisualElementRenderer`1[TElement].SetElement (TElement element) [0x00110] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.iOS\VisualElementRenderer.cs:188 "
<?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="TPApp.gui.pages.PageHome"
xmlns:local="clr-namespace:TPApp.gui.pages"
xmlns:carousel="clr-namespace:TPApp.gui.pages.HomeCarousel"
xmlns:lang="clr-namespace:TPApp.gui.lang;assembly=TPApp"
xmlns:catview="clr-namespace:TPApp.gui.views.category;assembly=TPApp"
xmlns:carouselsync="clr-namespace:Syncfusion.SfCarousel.XForms;assembly=Syncfusion.SfCarousel.XForms"
BackgroundColor="{StaticResource tpAppBackgroundColor}">
<ContentPage.Resources>
<ResourceDictionary>
<DataTemplate x:Key="tpProductItemTemplate">
<Label Text="{Binding sProductName}" TextColor="Black" />
</DataTemplate>
</ResourceDictionary>
</ContentPage.Resources>
<ListView x:Name="tpVCatList" HasUnevenRows="true">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Label Text="{Binding sName}"></Label>
<carouselsync:SfCarousel x:Name="tpProductCarousel" HeightRequest="400" WidthRequest="400" BackgroundColor="Aqua" ItemTemplate="{StaticResource tpProductItemTemplate}" ItemsSource="{Binding aProducts}"/>
<!-- <ListView ItemsSource="{Binding aProducts}" HasUnevenRows="true">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Label Text="PRODUCT" TextColor="Blue" />
<Label Text="{Binding sProductName}" TextColor="Blue" />
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView> -->
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentPage>
The following version works like charm:
<?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="TPApp.gui.pages.PageHome"
xmlns:local="clr-namespace:TPApp.gui.pages"
xmlns:carousel="clr-namespace:TPApp.gui.pages.HomeCarousel"
xmlns:lang="clr-namespace:TPApp.gui.lang;assembly=TPApp"
xmlns:catview="clr-namespace:TPApp.gui.views.category;assembly=TPApp"
xmlns:carouselsync="clr-namespace:Syncfusion.SfCarousel.XForms;assembly=Syncfusion.SfCarousel.XForms"
BackgroundColor="{StaticResource tpAppBackgroundColor}">
<ContentPage.Resources>
<ResourceDictionary>
<DataTemplate x:Key="tpProductItemTemplate">
<Label Text="{Binding sProductName}" TextColor="Black" />
</DataTemplate>
</ResourceDictionary>
</ContentPage.Resources>
<ListView x:Name="tpVCatList" HasUnevenRows="true">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Label Text="{Binding sName}"></Label>
<!-- <carouselsync:SfCarousel x:Name="tpProductCarousel" HeightRequest="400" WidthRequest="400" BackgroundColor="Aqua" ItemTemplate="{StaticResource tpProductItemTemplate}" ItemsSource="{Binding aProducts}"/> -->
<ListView ItemsSource="{Binding aProducts}" HasUnevenRows="true">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Label Text="PRODUCT" TextColor="Blue" />
<Label Text="{Binding sProductName}" TextColor="Blue" />
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentPage>
Did I miss somewhere a initialization oder something?
I checked the following based on the example you provided me:
- References are available, Packages are added, the Renderer is initialized in AppDelegate via
new SfCarouselRenderer()
Do you have any other ideas? :/
Thanks very much,
Alex
