EducaSwift

Variables of type Date handle date and time for us, which can be a complex topic due to the various formats, languages, and time zones used around the world.

Creating Date with the current time

The first step in working with dates and times is to create a Date object. This object has several initializers, the first one we'll see is the parameterless initializer, which returns the current date and time.

let now = Date()

print(now) // The console shows: 2021-01-22 19:12:28 +0000

The Timestamp concept

A Timestamp is simply the number of seconds that have passed since January 1, 1970, at 00:00 UTC. This is an international convention and is useful for working with dates because this number is independent of formats, languages, or time zones.

For example, we can initialize a Date object with the Timestamp parameter.

let date = Date(timeIntervalSince1970: 72)

print(date) // The console shows: 1970-01-01 00:01:12 +0000

As you can see, it shows the date 1 minute and 12 seconds after January 1, 1970, at 00:00. The current Timestamp is approximately 1734966571.

Date formatter

To display dates and times in different formats, we can use the DateFormatter object. Let's see how it works.

let date = Date()

let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .medium
dateFormatter.timeStyle = .short

print(dateFormatter.string(from: date)) // The console shows: Jan 22, 2021 at 8:20 PM

With DateFormatter, we can format both the date (dateStyle) and the time (timeStyle). Using the string(from:) method, we can display the date and time as a String. The format of this String depends on the device's settings, so we don't need to worry about translating anything.

Converting a String to Date

Sometimes, we got dates in String format. This isn't a problem if they always follow the same format, even in different languages, because we can convert them to a Date, and DateFormatter will display the date according to the device's settings.

To do this we'll use DateFormatter. First, we define the format we need to convert, and then we use the date(from:) method. The result is an Optional because there's a chance the conversion could fail if the format is incorrect or if it's not a valid date. Once we have our Date object, we can use it as shown below.

let dateString = "2021-01-22 19:29:47"

let dateFormatter = DateFormatter()

dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"

if let date = dateFormatter.date(from: dateString) {

  dateFormatter.dateStyle = .medium
  dateFormatter.timeStyle = .none

  print(dateFormatter.string(from: date)) // The console shows: Jan 22, 2021
}

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