gistfile1.txt

using NuGet.Packaging;
using NuGet.Frameworks;

using (var reader = new PackageArchiveReader(stream, true))
{
    var nuspecFile = reader.GetNuspecFile();
    if (nuspecFile == null)
        throw new Exception("Package does not contain a nuspec file");

    using (var s = reader.GetStream(nuspecFile))
    {
        var manifest = Manifest.ReadFrom(s, false);

        return (
            manifest,
            reader.GetSupportedFrameworks().ToArray()
        );
    }
}