Unity. Android. Save files disappears after updating an App

Question

I'm creating pretty simple game in Unity, and want to save results, time, etc. I use System.IO for it, and everything works fine, but when i update my app from '.apk' all the results disappear.

So how can i create file, which won't be deleted after update?

public static void Save()
{
    string[] lines = new string[] {
        Language,
        First_Test.ToString(),
        Last_Test.ToString(),
        MakeLine(ref Attention_Results),
        MakeLine(ref Memory_Results),
        MakeLine(ref Reaction_Results),
        Attention_Best.ToString(),
        Memory_Best.ToString(),
        Reaction_Best.ToString(),
        LastSend.ToString(),
        UserName,
        FlyTime.ToString() };

    File.WriteAllLines(Application.persistentDataPath+ @"/Progres.save", lines);
}

Answer 1

EDIT: Depending on your needs you may want to change the order of the potential directories and even favor external storage. If so please look at @LoungeKatt answer.

If you don't want to use the PlayerPrefs (which is I think the most robust available solution), you can always write directly into the user device.

WARNING: keep in mind doing it this way is far from a perfect solution ! The user can delete and edit the files you save and this is more of a workaround than a real answer.

Anyway, since the internal files directory paths changes from one Android device to another, you can use a small script to find it :

public static string GetAndroidInternalFilesDir()
{
    string[] potentialDirectories = new string[]
    {
        "/mnt/sdcard",
        "/sdcard",
        "/storage/sdcard0",
        "/storage/sdcard1"
    };

    if(Application.platform == RuntimePlatform.Android)
    {
        for(int i = 0; i < potentialDirectories.Length; i++)
        {
            if(Directory.Exists(potentialDirectories[i]))
            {
                return potentialDirectories[i];
            }
        }
    }
    return "";
}

Hope this helps,

Answer 2

Samsung and many other Android devices use a serial number as the mount point for external sdcards. Building on @Kardux's (original) answer for internal storage, the following will favor external storage (without a specific directory), then search for the internal sdcard as a fallback.

public static string GetAndroidInternalFilesDir()
{
    string[] potentialDirectories = new string[]
    {
        "/storage",
        "/sdcard",
        "/storage/emulated/0",
        "/mnt/sdcard",
        "/storage/sdcard0",
        "/storage/sdcard1"
    };

    if(Application.platform == RuntimePlatform.Android)
    {
        for(int i = 0; i < potentialDirectories.Length; i++)
        {
            if(Directory.Exists(potentialDirectories[i]))
            {
                return potentialDirectories[i];
            }
        }
    }
    return "";
}

Note: This assumes the external storage directory appears first in a directory list. It then prioritizes the attempts to access storage by likelihood of success and adds /storage/emulated/0, which many devices can access when unable to access /sdcard.