Ios 如何将日期选择器的最小日期设置为从今天起一个月

我在xcode7.3.1中使用swift。我想将日期选择器的最小日期设置为从今天起一个月。我正在使用以下代码。我认为这是不正确的方法。您能在此场景中帮助我吗

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

试试这个功能

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

试试这个功能

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

喜欢

    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

你得到了

你喜欢吗

    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

你得到了

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只需将单位更改为月份，将值更改为-1，只需将单位更改为月份，将值更改为-1