比较NSDate

Question

我想比较一下两个NSDates，但是每一个日期显示都比todaysDate“早”。有什么想法吗？

let compareResult = self.todaysDate.compare(self.date)

if compareResult == NSComparisonResult.OrderedDescending {
println("Today is later than date2")
} else {
println("Future")
}

获得"todaysDate“

let todaysDate = NSDate()
let calendar = NSCalendar.currentCalendar()
    let components = calendar.components(.CalendarUnitHour | .CalendarUnitMinute | .CalendarUnitMonth | .CalendarUnitYear | .CalendarUnitDay, fromDate: todaysDate)
let hour = components.hour
let minutes = components.minute
let month = components.month
let year = components.year
let day = components.day
println(todaysDate)

这张印刷品是：

2014-11-12 14:48:48 +0000

“日期”的印刷品是：

2014-10-24 07:24:41 +0000

这是在一个Parse.com服务器上。

谢谢

Answer 1

我认为您可能是在向后解释compare的结果。看看这个。每个asserts都通过：

let today = NSDate()
let tomorrow = today.dateByAddingTimeInterval(24 * 60 * 60)
let yesterday = today.dateByAddingTimeInterval(-24 * 60 * 60)

assert(today.compare(tomorrow)  == .OrderedAscending)     // today < tomorrow
assert(today.compare(yesterday) == .OrderedDescending)    // today > yesterday
assert(today.compare(today)     == .OrderedSame)          // today == today

Answer 2

如果您想支持==、<、>、<=或NSDate的>=，只需在某个地方声明如下：

public func ==(lhs: NSDate, rhs: NSDate) -> Bool {
    return lhs === rhs || lhs.compare(rhs) == .OrderedSame
}

public func <(lhs: NSDate, rhs: NSDate) -> Bool {
    return lhs.compare(rhs) == .OrderedAscending
}

extension NSDate: Comparable { }

实现==和<可以让Comparable推断其他比较运算符。

用法：

let date1 = NSDate()
let date2 = NSDate()

println(date2 > date1) // true
println(date2 < date1) // false
println(date2 == date2) // true

Answer 3

尝尝这个!通过将不同的日期分配给strdate，可以检查不同的日期。

    todaysDate = NSDate()
    println(todaysDate)

    var dateformmatter:NSDateFormatter = NSDateFormatter()
    dateformmatter.dateFormat = "yyyy-MM-dd HH:mm:ss";
    let strdate:NSString = "2014-12-12 07:24:41";
    date = dateformmatter.dateFromString(strdate)!;
    println(date)

    let compareResult = todaysDate.compare(date)

    if compareResult == NSComparisonResult.OrderedDescending {
        println("Today is later than date2")
    } else {
        println("Future")
    }