Reflection in universal windows platform (UWP) missing properties

问题

Type t = obj.GetType();
t.IsEnum;
t.IsPrimitive;
t.IsGenericType
t.IsPublic;
t.IsNestedPublic
t.BaseType
t.IsValueType

All of the above properties are missing in UWP. How do I check for these types now?

回答1:

A C# app that targets UWP uses two distinct sets of types. You already know the .NET types, like System.String, but the UWP specific types are actually COM interfaces under the hood. COM is the super-glue of interop, the basic reason why you can also write UWP apps in Javascript and C++. And C#, WinRT is an unmanaged api at its core.

The language projection for WinRT built into the .NET Framework makes that nasty little detail highly invisible. Some WinRT types are easy to identify, anything in the Windows namespace for example. Some can be both, a System.String can be both a .NET type and wrap a WinRT HSTRING. The .NET Framework automagically figures this out by itself.

Very invisible, but there are some cracks in the spackle. The Type class is one of them, Reflection for COM types is difficult. Microsoft could not hide the big difference between the two and had to create the TypeInfo class.

You'll find all the missing properties back in that class. Some silly sample code that shows it at work in a UWP app:

using System.Reflection;
using System.Diagnostics;
...

    public App()
    {
        Microsoft.ApplicationInsights.WindowsAppInitializer.InitializeAsync(
            Microsoft.ApplicationInsights.WindowsCollectors.Metadata |
            Microsoft.ApplicationInsights.WindowsCollectors.Session);
        this.InitializeComponent();
        this.Suspending += OnSuspending;
        // Reflection code...
        var t = typeof(string).GetTypeInfo();
        Debug.WriteLine(t.IsEnum);
        Debug.WriteLine(t.IsPrimitive);
        Debug.WriteLine(t.IsGenericType);
        Debug.WriteLine(t.IsPublic);
        Debug.WriteLine(t.IsNestedPublic);
        Debug.WriteLine(t.BaseType.AssemblyQualifiedName);
        Debug.WriteLine(t.IsValueType);
    }

Content of the VS Output window for this code:

False
False
False
True
False
System.Object, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
False

来源：https://stackoverflow.com/questions/33068373/reflection-in-universal-windows-platform-uwp-missing-properties

标签

reflection

uwp