Unity PlayerPrefs "extension" to save/retrieve dates/times

PlayerPrefsDateTime.cs

using System;
using UnityEngine;

public class PlayerPrefsDateTime {
    public static DateTime GetDateTime(string key, DateTime defaultValue = default(DateTime)) {
        if (PlayerPrefs.HasKey(key)) {
            string stringValue = PlayerPrefs.GetString(key);
            long longValue = Convert.ToInt64(stringValue);
            return DateTime.FromBinary(longValue);
        }
        else {
            return defaultValue;
        }
    }

    public static void SetDateTime(string key, DateTime value) {
        long longValue = value.ToBinary();
        string stringValue = longValue.ToString();
        PlayerPrefs.SetString(key, stringValue);
    }

    public static TimeSpan GetTimeSpan(string key, TimeSpan defaultValue = default(TimeSpan)) {
        if (PlayerPrefs.HasKey(key)) {
            string stringValue = PlayerPrefs.GetString(key);
            long longValue = Convert.ToInt64(stringValue);
            return TimeSpan.FromTicks(longValue);
        }
        else {
            return defaultValue;
        }
    }

    public static void SetTimeSpan(string key, TimeSpan value) {
        long longValue = value.Ticks;
        string stringValue = longValue.ToString();
        PlayerPrefs.SetString(key, stringValue);
    }
}