If you have Xamarin.iOS 1.8.365 installed along side your Visual Studio 2013 installation, you may have noticed problems with Windows Phone and Windows Store projects not displaying correctly in the designer. They would build ok, but you can’t set the debug target device, and the designer is broken and shows an “Invalid Markup” message, and there are a ton of Errors about the XAML. Errors like ‘The Name “PhoneApplicationPage” does not exist in the namespace…’, etc. Here’s a screenshot of what the errors look like:
To fix the problem, update to Xamarin.iOS 1.10 (info) or later. I can’t find a direct download link to the beta versions, but you can get it by telling your existing install to update via the “Beta” rather than “Stable” channel. To do that:
- Open Visual Studio 2013, and open the “Tools” | “Options” menu.
- On the “Xamarin” | “Android Settings” page, turn on the “Notify me about” checkbox.
- In the update channel drop-down box (reads “Stable by default) choose “Beta” updates.
- Click the “Check Now” link to check for updates now.
Repeat the process above, but on the “Xamarin” | “iOS Settings” page:
Allow the updates to be installed.
When the updates have completed, you can verify their versions in the Visual Studio “Help” | “About Microsoft Visual Studio” window.
Once updated, you should now be able to open an existing Windows Phone or Windows Store app in Visual Studio 2013 and no longer receive errors.