I am currently facing a problem with DateIntevalFormatter. When using the formatter with dateStyle = .long and timeStyle = .none the string output for some locales is not in the expected formatting. While the output for locales like en_US, de_de or fr_fr is as expected, locales like zh_Hans, ja and ko is not consistent with the dateStyle = .long of a DateFormatter. Using the dateTemplate/setLocalizedDateFormatFromTemplate() with template MMMMddyyyy seems to provide a consistent output. Is that maybe a bug in DateIntervalFormatter? Here some exemplary output of the below Playground code: It seems that the forum is not accepting some of the Chinese, Korean or Japanese characters, therefore you can only find the actual output of below code as attachment. Code output import UIKit func printDate(starteDate: Date, endDate: Date, locale: Locale) { let interval = DateIntervalFormatter() interval.locale = locale interval.dateTemplate = "MMMMddyyyy" let formatter = DateFormatter() formatter.locale = locale formatter.setLocalizedDateFormatFromTemplate("MMMMddyyyy") print("Locale: \(locale), template: MMMMddyyyy") print("Interval = \(interval.string(from: starteDate, to: endDate))") print("Format = \(formatter.string(from: starteDate))") print("Locale: \(locale), dateStyle: long") interval.dateStyle = .long interval.timeStyle = .none formatter.dateStyle = .long formatter.timeStyle = .none print("Interval = \(interval.string(from: starteDate, to: endDate))") print("Format = \(formatter.string(from: starteDate))") } let date1 = DateComponents(calendar: Calendar(identifier: Calendar.Identifier.gregorian), timeZone: TimeZone(abbreviation: "UTC"), year: 2019, month: 12, day: 20).date let date2 = DateComponents(calendar: Calendar(identifier: Calendar.Identifier.gregorian), timeZone: TimeZone(abbreviation: "UTC"), year: 2019, month: 12, day: 22).date printDate(starteDate: date1!, endDate: date2!, locale: Locale(identifier: "en_US")) printDate(starteDate: date1!, endDate: date2!, locale: Locale(identifier: "de_de")) printDate(starteDate: date1!, endDate: date2!, locale: Locale(identifier: "zh-Hans")) printDate(starteDate: date1!, endDate: date2!, locale: Locale(identifier: "ko")) printDate(starteDate: date1!, endDate: date2!, locale: Locale(identifier: "ja"))