TimeZones Split by Daylight Savings Time Participants

TimeZoneDisplay.swift

struct TimeZoneDisplay {
  
    struct TimeZone {
        let abbreviation: String
        let description: String
        let isDaylightSavingsParticipant: Bool
    }
  
    var timeZones = [TimeZone]()
  
    init(_ systemZones: Dictionary<String, String> = NSTimeZone.abbreviationDictionary) {
        timeZones = systemZones.map {
            TimeZone(
                abbreviation: $0.key,
                description: $0.value,
                isDaylightSavingsParticipant: NSTimeZone(
                    abbreviation: $0.key)?
                    .nextDaylightSavingTimeTransition != nil
            )
        }
    }
  
    lazy var participants = timeZones.filter { $0.isDaylightSavingsParticipant }
    lazy var nonParticipants = timeZones.filter { !$0.isDaylightSavingsParticipant }
}

let timeZoneDisplay = TimeZoneDisplay()

print("PARTICPANTS")
print(timeZoneDisplay.participants.map { $0.abbreviation })
print("NON-PARTICPANTS")
print(timeZoneDisplay.nonParticipants.map { $0.abbreviation })