[Xamarin] - Xamarin.Forms Project with .Net Standard 2.0

1. Install .NET Core 2.0 SDK 。
https://www.microsoft.com/net/download/core

2. Install Android 7.1 (API 25) SDK.

3. New .NET Standard Project With Nuget Update:
Microsoft.EntityFrameworkCore.2.0.0
Microsoft.EntityFrameworkCore.Sqlite.2.0.0
Xamarin.Forms.2.4.0.266-pre1

3. Library Project Initialization.

4. New Android Project With Nuget Update:
Microsoft.EntityFrameworkCore.2.0.0
Microsoft.EntityFrameworkCore.Sqlite.2.0.0
Xamarin.Forms.2.4.0.266-pre1

5.  Android Project Initialization.

6. APP Deploy.