Date Offset Extension

DateOffset.swift

import Foundation

extension Date {
    /// Returns a date that is `offset` days from this date.
    /// - Parameter offset: The number of days to add or subtract from `self`.
    /// - Returns: A new `Date` `offset` days days before or after `self`.
    func offset(_ offset: Int) -> Date {
        Calendar.current.date(byAdding: .day, value: offset, to: self)!
    }
}