您可以尝试这样的事情：

// db is my datacontext
var groupByOS = (from c in
                      (from d in db.DeviceInfo 
                       where d.Os.ToUpper().Contains("ANDROID") ||
                       d.Os.ToUpper().Contains("IOS")
                       group d by new { d.Os } into dev
                       select new
                       {
                         User = dev.Key.Os.ToUpper().Contains("ANDROID") ? "Android" : "iOS",
                         DeviceCount = dev.Count()
                       })
                 group c by new { c.User } into newgrp
                 select new
                 {
                     newgrp.Key.User,
                     Count = newgrp.Sum(q => q.DeviceCount)
                 }).ToList();