How to extract today, yesterday from Date() and make it localised like weekday and months? - ios

Question

I want to extract today, yesterday from date so it is localised automatically when I change language like which happens with weekdays and month.
Code for localised date that I am using:
let dateFormatter = Foundation.DateFormatter()
dateFormatter.dateFormat = "MMMM dd, yyyy"
dateFormatter.locale = Locale(identifier: "en_US_POSIX")
dateFormatter.timeZone = TimeZone(identifier: "UTC")
let dateStr = dateFormatter.string(from: datePickerView.date)
let timeStr = "00:00:00.000"
let dateString = NSString(format:"%# %#",dateStr,timeStr)
let mainDF = Foundation.DateFormatter()
mainDF.dateFormat = "MMMM dd, yyyy hh:mm:ss.SSS"
mainDF.locale = Locale(identifier: "en_US_POSIX")
mainDF.timeZone = TimeZone(identifier: "UTC")
let date = mainDF.date(from: dateString as String)
How to achieve this?

Answer 1

DateFormatter has special flag for that: doesRelativeDateFormatting, which renders dates in relative format, using locale set for this formatter.
… If a date formatter uses relative date formatting, where possible it
replaces the date component of its output with a phrase—such as
“today” or “tomorrow”—that indicates a relative date. The available
phrases depend on the locale for the date formatter; whereas, for
dates in the future, English may only allow “tomorrow,” French may
allow “the day after the day after tomorrow,” …
Example:
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale.autoupdatingCurrent // Using system locale
dateFormatter.doesRelativeDateFormatting = true // Enabling relative date formatting
// other dataFormatter settings here, irrelevant for example
dateFormatter.timeStyle = .none
dateFormatter.dateStyle = .medium
let now = Date()
let dateString: String = dateFormatter.string(from: now)
print("dateString: \(dateString)") // Prints `dateString: <Today in current locale>`