Conversion from UTCDateTime to Date or Time in AX

Here is an example of correct conversion between UTCDateTime value and Date and Time value which is associated with user preferred time zone:
public static void testDateTimeConversion()
{
    utcDateTime dateTime;
    date dateInUserTimeZone;
    TimeOfDay timeInUserTimeZone;

    dateTime = DateTimeUtil::utcNow();

    dateInUserTimeZone = DateTimeUtil::date(DateTimeUtil::applyTimeZoneOffset(dateTime, DateTimeUtil::getUserPreferredTimeZone()));
    timeInUserTimeZone = DateTimeUtil::time(DateTimeUtil::applyTimeZoneOffset(dateTime, DateTimeUtil::getUserPreferredTimeZone()));

    dateTime = DateTimeUtil::newDateTime(dateInUserTimeZone, timeInUserTimeZone, DateTimeUtil::getUserPreferredTimeZone());
}

UserConnection in D365fo

Its used when we need to commit our transaction wehen standared code doesn't Commit.
example :SalesQuotationEditLinesForm_Sales_Send > checkSales() , COC and try to write 
custom insert or update operation here while validation is failed our transactions doesn't commit

static void KlForRecordInserted(Args _args)
{
    UserConnection userConnection;
    CustTable custTable;
    ;
   
    ttsbegin;
   
    userConnection = new userConnection();
   
    custTable.clear();
    custTable.initValue();
    custTable.AccountNum = "000020";
    custTable.Name = "My Test Customer";
    custTable.setConnection(userConnection); // set userconnection
    custTable.insert();
   
    throw error("An error that causes a rollback");
    ttscommit;
}