How to format String to use Today and Yesterday instead of Date if appropriate in Swift?

Question

Context

I have a custom Stringify Method on Date formatting a given Date into a String. The result looks like this:

October 17th, 2022 at 1:27pm

However, when the Date is Today, Yesterday or Tomorrow, I would like to replace the actual Date with this specific String description. The result should look like this:

Today at 1:27pm

---

Code

extension Date {
    func stringify() -> String {
        let dateFormatter = DateFormatter()
        
        dateFormatter.dateStyle = .long
        dateFormatter.timeStyle = .short
        
        return dateFormatter.string(from: self)
    }
}

---

Question

• How can I achieve this behaviour, since DateFormatter is not supporting it?

Answer 1

As suggested in the comments, you can use DateFormatter for this, the trick is to turn on the doesRelativeDateFormatting flag.

let today = Date()
let yesterday = Calendar.current.date(byAdding: .day, value: -1, to: today)!
let tomorrow = Calendar.current.date(byAdding: .day, value: 1, to: today)!

let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .short
dateFormatter.doesRelativeDateFormatting = true

let todayString = dateFormatter.string(from: today)
print(todayString) // Today at 20:44

let yesterdayString = dateFormatter.string(from: yesterday)
print(yesterdayString) // Yesterday at 20:44

let tomorrowString = dateFormatter.string(from: tomorrow)
print(tomorrowString) // Tomorrow at 20:44