我通过一个简单的解决方法解决了这个问题，这里是解决方案.

I resolved this issue by doing a simple workaround and here is the solution.

在解决方案资源管理器中右键单击 XAML 文件并选择

Right-click the XAML file in the Solution Explorer and select

解决方案 1:打开方式..."源代码(文本)编辑器".

Solution 1: "Open With... > Source Code (Text) Editor".

还有一次这对我也有用:

and in another time this also worked for me:

解决方案 2:打开方式..."带编码的源代码(文本)编辑器"

Solution 2: "Open With... > Source Code (Text) Editor with Encoding"

即使没有安装额外的为 Xamarin.Forms 启用 XAML 语言"，此解决方法也为我提供了所需的 XAML 智能感知.扩展，甚至安装了 ReSharper 但已暂停.

This workaround gave me the desired XAML IntelliSense even without installing the extra "Enable XAML Language for Xamarin.Forms" extension and even with ReSharper installed but suspended.