无法获取向导生成的Xamarin / Visual Studio 2017应用程序进行编译

Question

I am trying to make my C++ application cross platform and port it from MFC. The code base should be pretty portable but I am having problems getting something that works well. Xamarin looks promising it seems like I could put my C++ code into a library and call it from C# code but so far I can't even get the most basic wizard created project to compile. I am on a windows 7 machine. I did a fresh install of visual studio 2017 community. I installed what I think are the correct components (see below) and had the wizard create a simple project. It then generates a long list of cryptic error messages. I am afraid I am not a C# programmer (if this looks promising I will have a reason to learn it). I have had some java android experience with android studio but never done NDK. So these are Greek to me and my web searches have not been fruitful. Does anyone have any idea what these messages mean? In the wizard I made these choices: 1) Visual C# Android 2) Android app (Xamarain) 3) Single view app 4) Android 5.0 lolypop And I got these error messages, without adding a line of my own code:

Severity Code Description Project File Line Suppression State Error CS0234 The type or namespace name 'Support' does not exist in the namespace 'Android' (are you missing an assembly reference?) App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 21 Active Error CS0234 The type or namespace name 'Support' does not exist in the namespace 'Android' (are you missing an assembly reference?) App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 5 Active Error CS0234 The type or namespace name 'Support' does not exist in the namespace 'Android' (are you missing an assembly reference?) App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 6 Active Error CS0246 The type or namespace name 'AppCompatActivity' could not be found (are you missing a using directive or an assembly reference?) App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 13 Active Error CS0115 'MainActivity.OnCreate(Bundle)': no suitable method found to override App1 C:\\Users\\Andre\\source\\repos\\App1\\App 1\\MainActivity.cs 16 Active Error CS0115 'MainActivity.OnCreateOptionsMenu(IMenu)': no suitable method found to override App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 28 Active Error CS0115 'MainActivity.OnOptionsItemSelected(IMenuItem)': no suitable method found to override App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 34 Active Error CS0103 The name 'SetContentView' does not exist in the current context App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 19 Active Error CS0103 The name 'FindViewById' does not exist in the current context App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 21 Active Error CS0234 The type or namespace name 'Support' does not exist in the namespace 'Android' (are you missing an assembly reference?) App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 21 Active Error CS0103 The name 'SetSupportActionBar' does not exist in the current context App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 22 Active Error CS0246 The type or namespace name 'FloatingActionButton' could not be found (are you missing a using directive or an assembly reference?) App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 24 Active Error CS0103 The name 'FindViewById' does not exist in the current context App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 24 Active Error CS0246 The type or namespace name 'FloatingActionButton' could not be found (are you missing a using directive or an assembly reference?) App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 24 Active Error CS0120 An object reference is required for the non-static field, method, or property 'MenuInflater.Inflate(int, IMenu)' App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 30 Active Error CS0103 The name 'Snackbar' does not exist in the current context App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\MainActivity.cs 48 Active Error CS0103 The name 'Snackbar' does not exist in the current context App1 C:\\Users\\Andre\\sou rce\\repos\\App1\\App1\\MainActivity.cs 48 Active Error NU1101 Unable to find package Xamarin.Android.Support.Design. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages App1 C:\\Users\\Andre\\source\\repos\\App1\\App1\\App1.csproj 1

I had android NDK (R15C) selected as well as Apache Ant (1.9.3) and C++ Android development tools

I did not select the emulator as I want to use my phone at this point. I also left out the other NDK versions. Do these correspond to the android version eg 5.0 lolypop?

Thanks in advance.

Answer 1

Last time, I upgraded VS & try test a xamarin app, I also faced this error. I goto Tools -> NuGet Package Manager -> Package Manager Settings. Check : Allow NuGet to download missing packages. Check : Automatically check for missing packages during build in Visual Studio. Then I rebuild app, NuGet check and download missing packages and build passed