Creating "today's date and last seven days' date" in to the String array in Swift Lang.

Last7Days.swift

let date = NSDate()                                     // Today's date.
let dateFormatter = NSDateFormatter()                   // Creating a dateFormatter object for making readable date
var array = [String]()                                  // Store the today's date and last 7 date.
let secondInADay: NSTimeInterval = 24 * 60 * 60         // A day NSTimeInterval
let timeInterval = date.timeIntervalSince1970           // Today's NSTimeInteval

dateFormatter.dateFormat = "EE-yyyyMMdd"                // Making a dateFormat
dateFormatter.locale = NSLocale(localeIdentifier:"us")  //
array.append(dateFormatter.stringFromDate(date))        // Adding today's date in to the array

for i in 1 ... 7 {                                      // Going back 7 days loops.
    let newDate = NSDate(timeIntervalSince1970: timeInterval - (secondInADay * NSTimeInterval(i)))  // going one day back
    array.append(dateFormatter.stringFromDate(newDate)) // Adding the current newDate in to the array
}
println(array)
// [Thu-20150507, Wed-20150506, Tue-20150505, Mon-20150504, Sun-20150503, Sat-20150502, Fri-20150501, Thu-20150430]