Swift:无法将类型 'NSDate' 的值转换为预期的参数类型 'NSDateComponents'

Question

谁知道我该如何解决这个问题？我收到此错误:

¨cannot convert value of type 'NSDate' to expected argument type 'NSDateComponents'¨ on line:

错误发生在以下行:

let competitionDay = userCalendar.dateFromComponents(competitionDate)!

这是一段更完整的代码摘录:

func Date() {               

    // Here we set the current date

    let date = NSDate()
    let calendar = NSCalendar.currentCalendar()
    let components = calendar.components([.Hour, .Minute, .Second, .Nanosecond], fromDate: date)
    let hour = components.hour
    let minutes = components.minute
    let month = components.month
    let year = components.year
    let day = components.day


    let currentDate = calendar.dateFromComponents(components)



    // here we set the due date. When the timer is supposed to finish
    // final Calendar value

        let userCalendar = NSCalendar.currentCalendar()


        let competitionDate:NSDate = myDatePicker.date


        competitionDate.timeIntervalSinceNow


        let competitionDay = userCalendar.dateFromComponents(competitionDate)!


    // Here we compare the two dates
    competitionDay.timeIntervalSinceDate(currentDate!)


    let dayCalendarUnit = calendar.components([NSCalendarUnit.Day, NSCalendarUnit.Hour, NSCalendarUnit.Minute], fromDate: date)


    //here we change the seconds to hours,minutes and days


    let competitionDayDifference = calendar.components([.Day, .Hour, .Minute],
            fromDate: currentDate!, toDate: competitionDay, options: NSCalendarOptions())

    //finally, here we set the variable to our remaining time
    let daysLeft = competitionDayDifference.day
    let hoursLeft = competitionDayDifference.hour
    let minutesLeft = competitionDayDifference.minute

Answer 1

在您原来的问题中，您调用 dateFromComponents , 它转换 NSDateComponents到 NSDate , 但提供了一个 competitionDate , 这已经是一个 NSDate .编译器只是简单地通知您这个错误。

--

顺便说一句，您填充一个 NSDateComponents与 .Hour , .Minute , .Second , 和 .Nanosecond来自NSDate , 但随后继续尝试保存对 components.year 的引用和 components.month和 components.day即使您没有指定这些组件应包含在 NSDateComponents 中.

--

下面你说:

It's a Countdown app and i had it running until i wanted a DatePicker to choose the date i am counting down. The competitionDate is the due date

如果这确实是您想要的，那么也许 NSDateComponents根本不需要。我可能只使用 NSDateComponentsFormatter方法 stringFromDate:toDate:向用户展示两个 NSDate 之间的时间量的漂亮字符串表示形式对象。

例如:

class ViewController: UIViewController {

    @IBOutlet weak var datePicker: UIDatePicker!
    @IBOutlet weak var label: UILabel!

    weak var timer: NSTimer?

    let formatter: NSDateComponentsFormatter = {
        let _formatter = NSDateComponentsFormatter()
        _formatter.allowedUnits = [.Year, .Month, .Day, .Hour, .Minute, .Second]
        _formatter.unitsStyle = .Full

        return _formatter
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        datePicker.date = NSDate().dateByAddingTimeInterval(1000) // initialize it to whatever you want
    }

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)

        timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: "didFireTimer:", userInfo: nil, repeats: true)
    }

    override func viewDidDisappear(animated: Bool) {
        super.viewDidDisappear(animated)

        timer?.invalidate()
    }

    func didFireTimer(timer: NSTimer) {
        label.text = formatter.stringFromDate(NSDate(), toDate: datePicker.date)
    }
}