Time comparisons in swift

Question

Question:

I need to compare 2 times - the current time and a set one. If the set time is in the future, find out how many minutes remain until said future time.

Answer 1

You have compare function to compare 2 NSDate to know which one is more recent. It returns NSCompareResults

enum NSComparisonResult : Int {
    case OrderedAscending
    case OrderedSame
    case OrderedDescending
}

Get distance (in seconds) from 2 NSDate, you have .timeIntervalSinceDate(). Then, you know how to convert to minutes, hours, ...

let date1 : NSDate = ... 
let date2 : NSDate = ...

let compareResult = date1.compare(date2)

let interval = date1.timeIntervalSinceDate(date2)

Answer 2

just to add to @tyt_g207's answer, I found the compare method, but hadn't found NSComparisonResult.OrderedDescending and the others. I used something like the modified below to check an expiration date against today's date

let date1 : NSDate = expirationDate 
let date2 : NSDate = NSDate() //initialized by default with the current date

let compareResult = date1.compare(date2)
if compareResult == NSComparisonResult.OrderedDescending {
    println("\(date1) is later than \(date2)")
}

let interval = date1.timeIntervalSinceDate(date2)

Answer 3

Use timeIntervalSinceDate of date on further date and pass the earlier date as parameter, this would give the time difference

Answer 4

    let dateComparisionResult: NSComparisonResult = currentDate.compare("Your Date")


    if dateComparisionResult == NSComparisonResult.OrderedAscending
    {
        // Current date is smaller than end date.
    }
    else if dateComparisionResult == NSComparisonResult.OrderedDescending
    {
        // Current date is greater than end date.

    }
    else if dateComparisionResult == NSComparisonResult.OrderedSame
    {
        // Current date and end date are same.

    }