[C#] textbox to .txt file

private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog OpenDialog = new OpenFileDialog();
            OpenDialog.Title = "Open";
            OpenDialog.Filter = "All Files|*.*";
            try
            {
                if (OpenDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                {
                    System.IO.StreamReader objReader;
                    objReader = new System.IO.StreamReader(OpenDialog.FileName);
                    textBox.Text = objReader.ReadToEnd();
                    objReader.Close();
                }
            }
            catch (ArgumentException ex)
            {
                MessageBox.Show("Invalid File Format");
            }
            catch (Exception ex)
            { }
        }

private void button2_Click(object sender, EventArgs e)
        {
            SaveFileDialog SaveDialog = new SaveFileDialog();
            SaveDialog.Title = "Save";

            try
            {
                if (SaveDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                {
                    StreamWriter sw = new StreamWriter(SaveDialog.FileName);
                    String[] contents = textBox.Lines.ToArray();
                    for (int i = 0; i < contents.Length; i++)
                    {
                        sw.WriteLine(contents[i]);
                    }
                    sw.Close();
                }
            }
            catch (Exception ex)
            {
            }
        }

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;