Una implementación funcional de Swift 3+ basada en la respuesta de alto mantenimiento y el comentario de vikingosegundo . Esta extensión de fecha también tiene opciones adicionales para cambiar año, mes y hora:
extension Date {
/// Returns a Date with the specified amount of components added to the one it is called with
func add(years: Int = 0, months: Int = 0, days: Int = 0, hours: Int = 0, minutes: Int = 0, seconds: Int = 0) -> Date? {
let components = DateComponents(year: years, month: months, day: days, hour: hours, minute: minutes, second: seconds)
return Calendar.current.date(byAdding: components, to: self)
}
/// Returns a Date with the specified amount of components subtracted from the one it is called with
func subtract(years: Int = 0, months: Int = 0, days: Int = 0, hours: Int = 0, minutes: Int = 0, seconds: Int = 0) -> Date? {
return add(years: -years, months: -months, days: -days, hours: -hours, minutes: -minutes, seconds: -seconds)
}
}
El uso para agregar solo un día según lo solicitado por OP sería:
let today = Date() // date is then today for this example
let tomorrow = today.add(days: 1)