Sets mobile build number to Unix time without last digit before building with Unity

BuildProcessorMobileBuildNumberSetter.cs

using UnityEditor;
using UnityEditor.Build;
using UnityEditor.Build.Reporting;
using UnityEngine;

public class BuildProcessorBuildNumberSetter : IPreprocessBuildWithReport
{
    public int callbackOrder => 0;

    public void OnPreprocessBuild(BuildReport report)
    {
        string caller = GetType().FullName + "." + nameof(OnPreprocessBuild);
        
        SetBuildNumber();

        void SetBuildNumber()
        { 
            // Set build number (iOS) and bundle version code (Android).
            //
            // NOTE: We drop last digit in order to prevent Google Play Store bundle version code upper limit of 100000
            // from preventing pushing new versions of the app.
            int unixTimeWithoutLastDigit = GetUnixTime() / 10;
#if UNITY_IOS
            PlayerSettings.iOS.buildNumber = unixTimeWithoutLastDigit.ToString();
            Debug.Log(caller + ": Modified iOS build number to: " + unixTimeWithoutLastDigit + " (Unix time without last digit)");
#elif UNITY_ANDROID
            PlayerSettings.Android.bundleVersionCode = unixTimeWithoutLastDigit;
            Debug.Log(caller + ": Modified Android bundle version code to: " + unixTimeWithoutLastDigit + " (Unix time without last digit)");
#endif   
                
            int GetUnixTime()
            {
                // From: http://answers.unity.com/answers/508931/view.html
                var epochStart = new System.DateTime(1970, 1, 1, 0, 0, 0, System.DateTimeKind.Utc);
                int unixTime = (int)(System.DateTime.UtcNow - epochStart).TotalSeconds;
                return unixTime;
            }
        }
    }
}