Swift-如何默认存储多个日期并检索?

let today = NSDate()
    let nextTue = Calendar.current.date(byAdding: .day, value: 6, to: today as Date)
    let formatter = DateFormatter()
    formatter.dateFormat = "yyyy-MM-dd"
    let todayString = formatter.string(from: today as Date)
    let nextString = formatter.string(from: nextTue!)
    formatter.dateFormat = "dd-MMM-yyyy"

    let calendar = NSCalendar(calendarIdentifier: NSCalendar.Identifier.gregorian)
    let components = calendar!.components([.weekday], from: today as Date)

    if components.weekday == 3 {
        print("Hello Tuesday")
        thisWeekDate.text! = "\(todayString) - \(nextString)"

    } else {
        print("It's not Tuesday")
    }