Most of the people who work with Xamarin’s Mono for Android in Visual Studio 2012 face a bug where Intellisense doesn’t work for AXML in source view.

One of the fix which worked for me is mentioned below.

1. Launch Visual Studio 2012
2. Open a solution with .AXML file in it
3. Now XML main menu should be visible on top
4. Open “Schemas…” menu
5. Sort by “File Name” column and see if “android-layout-xml” and “schemas.android.com.apk.res.android” are there. If found, skip to step 13
6. If not found, go to “Program Files” if 32-bit system or “Program Files (x86)” if 64-bit system.
7. Then go to “\MSBuild\Novell” or “\MSBuild\Xamarin\Android”
8. You should be able to see 2 files “android-layout-xml.xsd” and “schemas.android.com.apk.res.android.xsd”
9. Copy these 2 files to “\Microsoft Visual Studio 11.0\Xml\Schemas”
10. Again open the “Schemas…” menu as mentioned in steps 3&4
11. Now click “Add…” button and add these 2 files which should be located as mentioned in step 7 & 8
12. Now restart visual studio and the XML editor for design layout should work fine with Intellisense
13. From step 5….
14. If above steps don’t work, then close the Visual Studio 2012.
15. Now open “Developer command prompt for VS2012″ under Windows programs menu.
16. Type “Devenv /ResetSettings” without quotes.
17. Launch Visual Studio 2012 and see if Intellisense works.
18. If still not working, better go to Xamarin  forums and post there.
    
    
    

注意：visual studio安装目录下会有一个 monodroidcatalog.xml文件，是好改成下面一样:[本人是64位，32位没有(86)]

<SchemaCatalog xmlns="http://schemas.microsoft.com/xsd/catalog">
<Schema href="http://www.mamicode.com/%ProgramFiles(x86)%/MSBuild/Xamarin/Android/android-layout-xml.xsd" targetNamespace="http://schemas.android.com/apk/res/android" />
<Schema href="http://www.mamicode.com/%ProgramFiles(x86)%/MSBuild/Xamarin/Android/schemas.android.com.apk.res.android.xsd" targetNamespace="http://schemas.android.com/apk/res/android" />

<Association extension="axml" schema="%ProgramFiles(x86)%/MSBuild/Xamarin/Android/android-layout-xml.xsd" />
</SchemaCatalog>

红色标记部分是我手动加上去的。保存此文件后本人重启vs,然后新建一个.axml文件后可爱智能提示就出来了。。