Xojo.Core.Date.Constructor(secondsFrom1970 As Double, timezone As TimeZone)

From Xojo Documentation

Constructor
Xojo.Core.Date.Constructor(secondsFrom1970 As Double, timezone As Xojo.Core.TimeZone)

Creates a date using number of seconds from the first instant of 1 January 1970, GMT. Use a negative value to refer to specify a date before this date.

Sample Code

Convert a Unix Epoch value to a date:

Dim d As New Xojo.Core.Date(1490621730, Xojo.Core.TimeZone.Current)

Convert a date in the current time zone to GMT:

Dim myDate As Xojo.Core.Date = Xojo.Core.Date.Now // Get date for current time zone
Dim gmt As New Xojo.Core.TimeZone(0) // Get GMT time zone
Dim gmtDate As New Xojo.Core.Date(myDate.SecondsFrom1970, gmt)