I am trying to create a kind of form with several questions, the thing is that in each view there is a question and when moving to the next one, the type of question may or may not change, when my question type is the same as the next one I launch the same view, in Android it allows but in iOS I get the following problem:
ObjCRuntime.ObjCException
Message = Objective-C exception thrown. Name: NSInvalidArgumentException Reason: <Microsoft_Maui_Controls_Platform_Compatibility_ShellSectionRenderer: 0x116f56800> is pushing the same view controller instance (<Microsoft_Maui_Platform_PageViewController: 0x117869db0>) more than once which is not supported and is most likely an error in the application : com.geicam.asociados
Native stack trace:
0 CoreFoundation 0x00000001804ae0f8 __exceptionPreprocess + 172
1 libobjc.A.dylib 0x0000000180087db4 objc_exception_throw + 56
2 UIKitCore 0x0000000184bf9334 -[UINavigationController pushViewController:transition:forceImmediate:] + 3736
3 UIKitCore 0x0000000184bf832c -[UINavigationController pushViewController:animated:] + 756
4 libxamarin-dotnet-debug.dylib 0x0000000107f94bd4 xamarin_dyn_objc_msgSendSuper + 164
5 geicam.asociados 0x000000010589d95c interp_to_native_trampoline + 156
6 libmonosgen-2.0.dylib 0x00000001086ff6f8 ves_pinvoke_method + 584
7 libmonosgen-2.0.dylib 0x00000001086f3e84 mono_interp_exec_method + 3052
8 libmonosgen-2.0.dylib 0x00000001086f194c interp_runtime_invoke + 244
9 libmonosgen-2.0.dylib 0x000000010860abf0 mono_jit_runtime_invoke + 1116
10 libmonosgen-2.0.dylib 0x00000001087c6cb0 mono_runtime_try_invoke + 156
11 libmonosgen-2.0.dylib 0x00000001087c9d28 mono_runtime_invoke + 488
12 geicam.asociados 0x00000001058bf400 _ZL30native_to_managed_trampoline_9P11objc_objectP13objc_selectorPP11_MonoMethodj + 316
13 geicam.asociados 0x00000001059103bc -[UIKit_UIControlEventProxy BridgeSelector] + 44
14 UIKitCore 0x00000001853d58ec -[UIApplication sendAction:to:from:forEvent:] + 96
15 UIKitCore 0x0000000184ce23d0 -[UIControl sendAction:to:forEvent:] + 108
16 UIKitCore 0x0000000184ce2714 -[UIControl _sendActionsForEvents:withEvent:] + 268
17 UIKitCore 0x0000000184cdf188 -[UIButton _sendActionsForEvents:withEvent:] + 120
18 UIKitCore 0x0000000184ce13ac -[UIControl touchesEnded:withEvent:] + 392
19 UIKitCore 0x0000000185409354 -[UIWindow _sendTouchesForEvent:] + 900
20 UIKitCore 0x000000018540a878 -[UIWindow sendEvent:] + 3104
21 UIKitCore 0x00000001853ea238 -[UIApplication sendEvent:] + 580
22 UIKitCore 0x000000018546dff4 __dispatchPreprocessedEventFromEventQueue + 1684
23 UIKitCore 0x0000000185470e90 __processEventQueue + 5604
24 UIKitCore 0x00000001854697f0 __eventFetcherSourceCallback + 160
25 CoreFoundation 0x000000018040ee48 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24
26 CoreFoundation 0x000000018040ed90 __CFRunLoopDoSource0 + 172
27 CoreFoundation 0x000000018040e500 __CFRunLoopDoSources0 + 232
28 CoreFoundation 0x0000000180408be8 __CFRunLoopRun + 768
29 CoreFoundation 0x00000001804084d4 CFRunLoopRunSpecific + 572
30 GraphicsServices 0x000000018ef2aae4 GSEventRunModal + 160
31 UIKitCore 0x00000001853d0a28 -[UIApplication _run] + 868
32 UIKitCore 0x00000001853d46b0 UIApplicationMain + 124
33 libxamarin-dotnet-debug.dylib 0x0000000107f4fa84 xamarin_UIApplicationMain + 60
34 libmonosgen-2.0.dylib 0x0000000108700abc do_icall + 316
35 libmonosgen-2.0.dylib 0x00000001086ff35c do_icall_wrapper + 356
36 libmonosgen-2.0.dylib 0x00000001086f3dac mono_interp_exec_method + 2836
37 libmonosgen-2.0.dylib 0x00000001086f194c interp_runtime_invoke + 244
38 libmonosgen-2.0.dylib 0x000000010860abf0 mono_jit_runtime_invoke + 1116
39 libmonosgen-2.0.dylib 0x00000001087c5c9c mono_runtime_invoke_checked + 148
40 libmonosgen-2.0.dylib 0x00000001087cd27c mono_runtime_exec_main_checked + 116
41 libmonosgen-2.0.dylib 0x000000010865ee78 mono_jit_exec + 364
42 libxamarin-dotnet-debug.dylib 0x0000000107f93a38 xamarin_main + 2320
43 geicam.asociados 0x0000000105981560 main + 72
44 dyld 0x000000010654d544 start_sim + 20
45 ??? 0x0000000106652154 0x0 + 4402258260
46 ??? 0xb162800000000000 0x0 + 12781919429919244288
Origin = Microsoft.iOS
Whenever you press the next button, it does the following function:
public async void CargarView(int id)
{
switch ((enumFormTipoPregunta)id)
{
case enumFormTipoPregunta.TextoCorto:
var navigationTextoCorto = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaTCortoView)}", navigationTextoCorto);
break;
case enumFormTipoPregunta.Parrafo:
var navigationParrafo = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaTLargoView)}", navigationParrafo);
break;
case enumFormTipoPregunta.Opcion:
var navigationParameter = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaOpcionView)}", navigationParameter);
break;
case enumFormTipoPregunta.Multiple:
var navigationFormulario = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaMultipleView)}", navigationFormulario);
break;
case enumFormTipoPregunta.Desplegable:
var navigationDesplegable = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaOpcionView)}", navigationDesplegable);
break;
case enumFormTipoPregunta.Multiple2Col:
var navigationMultiple2Col = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaMultipleView)}", navigationMultiple2Col);
break;
case enumFormTipoPregunta.Numerico:
var navigationNumerico = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaNumericaView)}", navigationNumerico);
break;
case enumFormTipoPregunta.Valoracion:
var navigationValoracion = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaValoracionView)}", navigationValoracion);
break;
case enumFormTipoPregunta.Fecha:
var navigationFecha = new Dictionary<string, object>
{
{ "Formulario", formul },
{ "Contador", cfo },
{ "Respuesta", gRespu }
};
await Shell.Current.GoToAsync($"{nameof(PreguntaFechaView)}", navigationFecha);
break;
default:
break;
}
}
I've been doing some research and the problem is that iOS doesn't allow you to launch the same view. so any idea how I could change it so that it works on both devices?
You can use DataTemplateSelector to change view:
Create a model
namespace MauiApp2.Model
{
public class Question
{
public string? QuestionText { get; set; }
public string? QuestionType { get; set; } // e.g., "Text", "MultipleChoice", etc.
public List<string>? Options { get; set; } // For multiple choice questions
}
}
Then viewmodel
namespace MauiApp2.VieModel
{
public class QuestionsViewModel : INotifyPropertyChanged
{
public ObservableCollection<Question> Questions { get; set; }
public QuestionsViewModel()
{
CreateQuestions();
}
void CreateQuestions()
{
Questions = new ObservableCollection<Question>
{
new Question() { QuestionText = "What's your name?", QuestionType = "Text" },
new Question() { QuestionText = "Your hobbies", QuestionType = "MultipleChoice", Options=new List<string>(){"Game", "Photography", "Cycling" } },
new Question() { QuestionText = "How old are you?", QuestionType = "Text" },
new Question() { QuestionText = "Your favourite foods ", QuestionType = "MultipleChoice",Options=new List<string>(){"Beef", "Hamburger", "Salad" } }
};
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
}
Create a DataTemplateSelector
namespace MauiApp2
{
public class QuestionTemplateSelector : DataTemplateSelector
{
public DataTemplate TextQuestionTemplate { get; set; }
public DataTemplate MultipleChoiceQuestionTemplate { get; set; }
protected override DataTemplate OnSelectTemplate(object item, BindableObject container)
{
var question = item as Question;
switch (question?.QuestionType)
{
case "Text":
return TextQuestionTemplate;
case "MultipleChoice":
return MultipleChoiceQuestionTemplate;
default:
return null;
}
}
}
}
Use them in MainPage
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:vm="clr-namespace:MauiApp2.VieModel"
xmlns:local="clr-namespace:MauiApp2"
x:Class="MauiApp2.MainPage">
<ContentPage.BindingContext>
<vm:QuestionsViewModel/>
</ContentPage.BindingContext>
<ContentPage.Resources>
<DataTemplate x:Key="textQuestionTemplate">
<StackLayout>
<Frame HasShadow="True"
BorderColor="DarkGray"
CornerRadius="5"
Margin="20"
HeightRequest="300"
HorizontalOptions="Center"
VerticalOptions="CenterAndExpand">
<StackLayout>
<Label Text="{Binding QuestionText}" />
<Entry Placeholder="Enter your answer here" />
</StackLayout>
</Frame>
</StackLayout>
</DataTemplate>
<DataTemplate x:Key="multipleChoiceQuestionTemplate">
<StackLayout>
<Frame HasShadow="True"
BorderColor="DarkGray"
CornerRadius="5"
Margin="20"
HeightRequest="300"
HorizontalOptions="Center"
VerticalOptions="CenterAndExpand">
<StackLayout>
<Label Text="{Binding QuestionText}" />
<ListView ItemsSource="{Binding Options}" />
</StackLayout>
</Frame>
</StackLayout>
</DataTemplate>
<local:QuestionTemplateSelector x:Key="questionTemplateSelector"
TextQuestionTemplate="{StaticResource textQuestionTemplate}"
MultipleChoiceQuestionTemplate="{StaticResource multipleChoiceQuestionTemplate}"/>
</ContentPage.Resources>
<StackLayout Margin="20">
<CarouselView ItemsSource="{Binding Questions}"
IndicatorView="indicatorView"
ItemTemplate="{StaticResource questionTemplateSelector}" />
<IndicatorView x:Name="indicatorView"
IndicatorColor="LightGray"
SelectedIndicatorColor="DarkGray"
HorizontalOptions="Center" />
</StackLayout>
</ContentPage>
Hope it can help you!