[Unity]ファイルにアプリの起動回数を保存

example.cs

using System.IO;
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
	private string path;
	private string counter;
	
	void Start ()
	{
		path = Application.persistentDataPath + @"/test.txt";
		if (!File.Exists (path)) {
			counter = "1";
		} else {
			string txt = File.ReadAllText (path);
			counter = (int.Parse (txt) + 1).ToString();
		}
		File.WriteAllText (path, counter);
	}
	
	void OnGUI () {
		GUI.TextArea(new Rect(5, 5, Screen.width, 50), counter + ":"+ path);
	}
}