how to set date picker minimum date with one month back from today

问题

I am using swift with xcode7.3.1 . I want to set my date picker minimum date must be one month back from today.I am using the following code.I think its not correct way.Could you please help me on this scenario.

  let calendar = NSCalendar.currentCalendar()
  let oneMonthBack = calendar.dateByAddingUnit(.Day, value: -30, toDate: NSDate(), options: [])
  datePicker.minimumDate = oneMonthBack

回答1:

try this function

func previousMonth(sender : AnyObject) {
        let currentCalendar = NSCalendar.currentCalendar()
        let dateComponents = NSDateComponents()
        dateComponents.month = -1
        let oneMonthBack = currentCalendar.dateByAddingComponents(dateComponents, toDate: NSDate(), options: [])!
    }

回答2:

do like

    let calendar: NSCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
     calendar.timeZone = NSTimeZone(name: "UTC")!
     let components: NSDateComponents = NSDateComponents()
    components.calendar = calendar
     components.month = -1 // this is for month
    let minDate: NSDate = calendar.dateByAddingComponents(components, toDate: NSDate(), options: NSCalendarOptions(rawValue: 0))!
     print("minDate: \(minDate)")
     datePicker.minimumDate = minDate

you get the output of

来源：https://stackoverflow.com/questions/38781435/how-to-set-date-picker-minimum-date-with-one-month-back-from-today