Creating valid dates using the Swift language

Date is the type we use to handle calendar information in Swift. It stores all the information needed to represent a specific point in time, independent of any calendar or time zone, by representing a time interval relative to an absolute reference date.

var birthday: Date = Date.now()

In an application’s user interface, it is common to handle dates and times by picking specific calendar values to represent the date. A user will usually choose a day, a month, an hour, or a minute, for example and then your application will have to transform that value into a valid Date value.

That’s where DateComponents comes in handy. It allows you to represent a date or time in terms of units, which can then be evaluated in a calendar system and time zone.

var components = DateComponents()

components.year = 2025
components.month = 6
components.day = 9

components.hour = 10
components.minute = 00

To evaluate a DateComponent value in a calendar system and time zone use the Calendar type and the type method date(from:).

let calendar = Calendar.current

if let date = calendar.date(from: components) {
    print("Valid date: \(date)")
} else {
    print("Invalid date")
}

It can also be done the other way around. DateComponents has a calendar property. By assigning a calendar value to it, you can access the date property to obtain a validated date calculated using the current components and the assigned calendar.

var components = DateComponents()

components.year = 2025
components.month = 6
components.day = 16

components.calendar = Calendar(identifier: .gregorian)

if let date = components.date {
    print("The date is valid!")
} else {
    print("The date is not valid...")
}