使用Swift的NSDate比较

我正在开发一个应用程序，需要检查到期日作业。我想知道到期日是否在下周内，如果是，然后执行操作。
我可以找到的大多数文档是在Objective-C，我不知道如何在Swift中做。
谢谢您的帮助！！

我喜欢使用扩展，使代码更可读。这里有一些NSDate扩展，可以帮助清理你的代码，使其易于理解。我把它放在sharedCode.swift文件中：

extension NSDate {
    func isGreaterThanDate(datetoCompare: NSDate) -> Bool {
        //Declare Variables
        var isGreater = false

        //Compare Values
        if self.compare(datetoCompare) == NSComparisonResult.OrderedDescending {
            isGreater = true
        }

        //Return Result
        return isGreater
    }

    func isLessthanDate(datetoCompare: NSDate) -> Bool {
        //Declare Variables
        var isLess = false

        //Compare Values
        if self.compare(datetoCompare) == NSComparisonResult.OrderedAscending {
            isLess = true
        }

        //Return Result
        return isLess
    }

    func equalToDate(datetoCompare: NSDate) -> Bool {
        //Declare Variables
        var isEqualTo = false

        //Compare Values
        if self.compare(datetoCompare) == NSComparisonResult.OrderedSame {
            isEqualTo = true
        }

        //Return Result
        return isEqualTo
    }

    func addDays(daysToAdd: Int) -> NSDate {
        let secondsInDays: NSTimeInterval = Double(daysToAdd) * 60 * 60 * 24
        let dateWithDaysAdded: NSDate = self.dateByAddingTimeInterval(secondsInDays)

        //Return Result
        return dateWithDaysAdded
    }

    func addHours(hoursToAdd: Int) -> NSDate {
        let secondsInHours: NSTimeInterval = Double(hoursToAdd) * 60 * 60
        let dateWithHoursAdded: NSDate = self.dateByAddingTimeInterval(secondsInHours)

        //Return Result
        return dateWithHoursAdded
    }
}

现在如果你可以这样做：

//Get Current Date/Time
var currentDateTime = NSDate()

//Get Reminder Date (which is Due date minus 7 days lets say)
var reminderDate = dueDate.addDays(-7)

//Check if reminderDate is Greater than Right Now
if(reminderDate.isGreaterThanDate(currentDateTime)) {
    //Do Something...
}