Hello,
I'm trying to implement an UWP application on the Xamarin Shared project.
After doing:
ApplicationBootstrapper.InitializeIfNeeds<MY_PROJECTXamarinUwpModule>();
...
Xamarin.Forms.Forms.Init(e);
...
ConfigureFlurlHttp();
in the App.xaml.cs
And:
LoadApplication(new MY_PROJECT_NAMESPACE.App());
in the MainPage.xaml.cs
the module:
namespace MY_PROJECT
{
[DependsOn(typeof(MY_PROJECTXamarinSharedModule))]
public class MY_PROJECTXamarinUwpModule : AbpModule
{
public override void Initialize()
{
IocManager.RegisterAssemblyByConvention(typeof(MY_PROJECTXamarinUwpModule).GetAssembly());
}
}
}
and the Locale.cs:
public class Locale : ILocale, ISingletonDependency
{
public void SetLocale(CultureInfo ci)
{
Thread.CurrentThread.CurrentCulture = ci;
Thread.CurrentThread.CurrentUICulture = ci;
}
public CultureInfo GetCurrentCultureInfo()
{
var netLanguage = "en";
if (Windows.System.UserProfile.GlobalizationPreferences.Languages.Count > 0)
{
var pref = Windows.System.UserProfile.GlobalizationPreferences.Languages[0];
netLanguage = UwpToDotnetLanguage(pref);
}
// this gets called a lot - try/catch can be expensive so consider caching or something
System.Globalization.CultureInfo ci = null;
try
{
ci = new System.Globalization.CultureInfo(netLanguage);
}
catch (CultureNotFoundException e1)
{
// iOS locale not valid .NET culture (eg. "en-ES" : English in Spain)
// fallback to first characters, in this case "en"
try
{
var fallback = ToDotnetFallbackLanguage(new PlatformCulture(netLanguage));
Console.WriteLine(netLanguage + " failed, trying " + fallback + " (" + e1.Message + ")");
ci = new System.Globalization.CultureInfo(fallback);
}
catch (CultureNotFoundException e2)
{
// iOS language not valid .NET culture, falling back to English
Console.WriteLine(netLanguage + " couldn't be set, using 'en' (" + e2.Message + ")");
ci = new System.Globalization.CultureInfo("en");
}
}
return ci;
//return new CultureInfo(Windows.System.UserProfile.GlobalizationPreferences.Languages[0]);
}
string UwpToDotnetLanguage(string androidLanguage)
{
Console.WriteLine("Android Language:" + androidLanguage);
var netLanguage = androidLanguage;
//certain languages need to be converted to CultureInfo equivalent
switch (androidLanguage)
{
case "ms-BN": // "Malaysian (Brunei)" not supported .NET culture
case "ms-MY": // "Malaysian (Malaysia)" not supported .NET culture
case "ms-SG": // "Malaysian (Singapore)" not supported .NET culture
netLanguage = "ms"; // closest supported
break;
case "in-ID": // "Indonesian (Indonesia)" has different code in .NET
netLanguage = "id-ID"; // correct code for .NET
break;
case "gsw-CH": // "Schwiizertüütsch (Swiss German)" not supported .NET culture
netLanguage = "de-CH"; // closest supported
break;
// add more application-specific cases here (if required)
// ONLY use cultures that have been tested and known to work
}
Console.WriteLine(".NET Language/Locale:" + netLanguage);
return netLanguage;
}
string ToDotnetFallbackLanguage(PlatformCulture platCulture)
{
Console.WriteLine(".NET Fallback Language:" + platCulture.LanguageCode);
var netLanguage = platCulture.LanguageCode; // use the first part of the identifier (two chars, usually);
switch (platCulture.LanguageCode)
{
case "gsw":
netLanguage = "de-CH"; // equivalent to German (Switzerland) for this app
break;
// add more application-specific cases here (if required)
// ONLY use cultures that have been tested and known to work
}
Console.WriteLine(".NET Fallback Language/Locale:" + netLanguage + " (application-specific)");
return netLanguage;
}
}
It compiles perfectly but when I try to exectute the program, I get "System.ArgumentNullException : 'Value cannot be null.'" in the:
return new AsyncCommand(new Command(async () => await func()));
line 31 of the MY_PROJECT.Mobile.Shared\Core\Threading\AsyncCommand.cs file
and here is the stacktrace: [Code externe]
MY_PROJECT.Mobile.Shared.dll!MY_PROJECT.Core.Threading.AsyncCommand.Create.AnonymousMethod__0() Ligne 31 C# [Code externe] MY_PROJECT.Mobile.Shared.dll!MY_PROJECT.Core.Threading.AsyncCommand.Execute(object parameter) Ligne 26 C# MY_PROJECT.Mobile.Shared.dll!MY_PROJECT.Commands.HttpRequestCommand.Execute(object parameter) Ligne 27 C# MY_PROJECT.Mobile.Shared.dll!MY_PROJECT.Behaviors.InvokeCommandAction.Execute(object sender, object parameter) Ligne 58 C# MY_PROJECT.Mobile.Shared.dll!MY_PROJECT.Behaviors.EventHandlerBehavior.OnEvent(object sender, object eventArgs) Ligne 104 C# [Code externe]
please Help
Thanks in advance
5 Answer(s)
-
0
hi,
I'm not experienced in UWP development. but if you get exception in
AsyncCommandyou can directly use to see if the problem isAsyncCommandor not. Looks like an expected parameter is not there (maybe not coming from XAML)public class AsyncCommand : ICommand { public static AsyncCommand Create(Func<System.Threading.Tasks.Task> func) { var funcName = nameof(func); /*put debugger to see the parameters*/ var command = new Command(async () => await func()); var asyncCommand = new AsyncCommand(command); return asyncCommand; } }Important suggestion:
- Close Visual Studio
- Delete all bin and obj folders in the solution directory
- Open solution and try again.
And these can give clue;
https://forums.xamarin.com/discussion/128306/value-cannot-be-null-parameter-name-type
https://forums.xamarin.com/discussion/106106/how-can-i-resolve-value-cannot-be-null-parameter-name-source-exception-xamarin-forms-latest-ver
https://stackoverflow.com/questions/22438816/cannot-create-custom-command-in-wpf-application
-
0
Microsoft finally admits Windows Phone is dead! Xamarin developers can safely stop supporting UWP projects. So don't waste your time building app for Windows 10 Mobile!
See https://support.microsoft.com/en-us/help/4485197/windows-10-mobile-end-of-support-faq
-
0
Thank You @alper
but I'm not using UWP for Windows phone development, but for Windows 10 App Store Application.
So what do you suggest me to do? I use WPF? And How to reuse Xamarin Shared Project In a desktop Application. Or have you a sample implementing the use of Session and Services?
Thanks in advance.
-
0
Actually I'm not experienced in Windows 10 development. To narrow down the issue, you can directly use
new Command(async () => await func())instead of the shortcutAsyncCommand. -
0
Hi @dfielec,
I'm also interested to add UWP support to Xamarin Form project. I have a good experience on Windows 10 development with UWP and the benefits of using windows store apps (Line Of Buisness apps can be deliver very easily to a dedicated company)
Did you overcome your last issue ? Do you have some display artefacts or lantencies in comparison to android or ios apps ?
Tks in advance.
