Unity read & write text files.

unityReadWriteFile.cs

using System.IO;

string path = "Assets/file.txt";

// Write to file
File.AppendAllText(path, System.String.Format("{0} {1} {3}\n", var1, var2, var3));
    
// Read from file
StreamReader sr = new StreamReader(path);
for (int i = 0; !sr.EndOfStream; i++) {
  string line = sr.ReadLine ();
  string[] Splitted = line.Split(new char[] {' '}, System.StringSplitOptions.RemoveEmptyEntries);
  record.Add (new Vector3 (float.Parse (Splitted [0]), float.Parse (Splitted [1]), float.Parse (Splitted [2])));
}