可以试试下面的代码吗?

Could you please try below code?

public void btn_Submit_Click(object sender, EventArgs e)
        {
            List<KeyValuePair<string, Tuple<int, int>>> d = new List<KeyValuePair<string, Tuple<int, int>>>
            {
                new KeyValuePair<string, Tuple<int, int>>("1",Tuple.Create<int,int>(1,1)),
                new KeyValuePair<string, Tuple<int, int>>("2",Tuple.Create<int,int>(2,2)),
                new KeyValuePair<string, Tuple<int, int>>("3",Tuple.Create<int,int>(3,3)),
                new KeyValuePair<string, Tuple<int, int>>("4",Tuple.Create<int,int>(4,4)),
                new KeyValuePair<string, Tuple<int, int>>("5",Tuple.Create<int,int>(5,5))
            };

            List<Coordinate> cv = new List<Coordinate>();

            foreach (KeyValuePair<string, Tuple<int, int>> entry in d)
            {
                Coordinate v = new Coordinate();

                v.Date_Time = DateTime.Now.ToString("dd/MM/yyyy hh/mm/ss");
                v.BeaconID = entry.Key;
                v.X_Coordinate = entry.Value.Item1.ToString();
                v.Y_Coordinate = entry.Value.Item2.ToString();
                cv.Add(v);
            }
            SaveValues(cv);
        }

    public void SaveValues(List<Coordinate> v)
            {
                XmlSerializer serializer = new XmlSerializer(typeof(List<Coordinate>), new XmlRootAttribute("Coordinates"));
                using (TextWriter textWriter = new StreamWriter(@"F:\Vista\Exporting into XML\Test1\Coordinates output.xml", true))
                {
                    serializer.Serialize(textWriter, v);
                }
                MessageBox.Show("Coordinates were exported successfully", "Message");//Let the user know the export was succesfull            
            }

更新代码以包含字典...

Updated code to have dictionary...

public void btn_Submit_Click(object sender, EventArgs e)
            {
                Dictionary<string, Tuple<int, int>> d = new Dictionary<string, Tuple<int, int>>();
            int X_Co = 1;
            int Y_Co = 1;
            var t = new Tuple<int, int>(X_Co, Y_Co);
            d.Add("1", t);

            X_Co = 2;
            Y_Co = 2;
            t = new Tuple<int, int>(X_Co, Y_Co);
            d.Add("2", t);

                List<Coordinate> cv = new List<Coordinate>();

                foreach (KeyValuePair<string, Tuple<int, int>> entry in d)
                {
                    Coordinate v = new Coordinate();

                    v.Date_Time = DateTime.Now.ToString("dd/MM/yyyy hh/mm/ss");
                    v.BeaconID = entry.Key;
                    v.X_Coordinate = entry.Value.Item1.ToString();
                    v.Y_Coordinate = entry.Value.Item2.ToString();
                    cv.Add(v);
                }
                SaveValues(cv);
            }

更新了代码，每个循环都有单独的文件.

Updated code to have separate files for every loop.

foreach (KeyValuePair<string, Tuple<int, int>> entry in d)
            {
                List<Coordinate> cv = new List<Coordinate>();
                Coordinate v = new Coordinate();

                v.Date_Time = DateTime.Now.ToString("dd/MM/yyyy hh/mm/ss");
                v.BeaconID = entry.Key;
                v.X_Coordinate = entry.Value.Item1.ToString();
                v.Y_Coordinate = entry.Value.Item2.ToString();
                cv.Add(v);
                SaveValues(cv);
            }