Question: I'm trying to do a release build for an IOS app using Xamarin.Forms in Visual Studio 2015. 

Under the iOS Build menu in the properties of the app, If I set the Linker behaviour Link SDK assemblies only or Link all assemblies - I get the following build error:

> 
> Failed to resolve assembly: 'System.Net.Http.Primitives,
>  Version=1.5.0.0, Culture=neutral,
>  PublicKeyToken=b03f5f7f11d50a3a' BlackhawkPlatform.App.iOS
> 
> 
> 

If I don't link any of the assemblies - the App builds fine but the output ipa is over 40mb big 0 uncompressed over 100mb and as such cannot be submitted to iTunes Connect.

I have the latest version installed of System.Net Client libraries and Xamarin Forms.

[![enter image description here](https://i.stack.imgur.com/wVOte.png)](https://i.stack.imgur.com/wVOte.png)

I have tried to skip the assembly link by using the command `--linkskip=System.Net.Http.Primitives` in the Additional mtouch argument box but that dos not work. 

Any idea how I can get around this please?

Answer: 
Found a solution which worked.

1. In Nuget package manager install the latest version of **Microsoft.BCL.Build** v1.0.21
2. then install the latest version of **Microsoft.Net.Http** v2.2.29

This worked for me.
I know this is an old thread... but here is what I found missing in my ios.csproj file

```
<Reference Include="System.Net.Http.Extensions">
  <HintPath>..\packages\Microsoft.Net.Http.2.2.29\lib\Xamarin.iOS10\System.Net.Http.Extensions.dll</HintPath>
</Reference>
<Reference Include="System.Net.Http.Primitives">
  <HintPath>..\packages\Microsoft.Net.Http.2.2.29\lib\Xamarin.iOS10\System.Net.Http.Primitives.dll</HintPath>
</Reference>

```