Finding the Difference in Time Between Two Nsdates Swift

Finding the difference in time between two NSDates Swift

Yes if you look at the second answer to your linked question you can do this:
let interval = laterDate.timeIntervalSinceDate(earlierDate)

Swift days between two NSDates

You have to consider the time difference as well. For example if you compare the dates 2015-01-01 10:00 and 2015-01-02 09:00, days between those dates will return as 0 (zero) since the difference between those dates is less than 24 hours (it's 23 hours).

If your purpose is to get the exact day number between two dates, you can work around this issue like this:

// Assuming that firstDate and secondDate are defined
// ...

let calendar = NSCalendar.currentCalendar()

// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDayForDate(firstDate)
let date2 = calendar.startOfDayForDate(secondDate)

let flags = NSCalendarUnit.Day
let components = calendar.components(flags, fromDate: date1, toDate: date2, options: [])

components.day  // This will return the number of day(s) between dates

Swift 3 and Swift 4 Version

let calendar = Calendar.current

// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDay(for: firstDate)
let date2 = calendar.startOfDay(for: secondDate)

let components = calendar.dateComponents([.day], from: date1, to: date2)

Get Time interval between two NSDate

Hope this can help you.

NSString *startDate = @"2016-02-24 10:25:11 +0000";
NSString *endDate = @"2016-02-24 10:26:11 +0000";

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss Z"];
NSDate *start = [formatter dateFromString:startDate];
NSDate *end = [formatter dateFromString:endDate];

NSTimeInterval interval = [end timeIntervalSinceDate:start];
NSLog(@"time interval:%f", interval);

How to calculate days difference between two NSDate objects in different time zones?

This is an odd case. You're looking for the difference in calendar dates between two Dates when those dates are evaluated in a specific time zone.

I did some playing, and came up with code that works for dates that fall in the same year:

let date = Date()

guard let nycTimeZone = TimeZone(abbreviation: "EST"),
  let nzTimeZone = TimeZone(abbreviation: "NZDT") else {
    fatalError()
}
var nycCalendar = Calendar(identifier: .gregorian)
nycCalendar.timeZone = nycTimeZone
var nzCalendar = Calendar(identifier: .gregorian)
nzCalendar.timeZone = nzTimeZone

let now = Date()

let nycDayOfYear = nycCalendar.ordinality(of: .day, in: .year, for: now)

var nzDayOfYear = nzCalendar.ordinality(of: .day, in: .year, for: now)

I'm using New York and Aukland, NZ as my time zones because as of the time of this writing, those zones are on different dates.

As of now (~12:00 PM on Feb 11, 2017 in US Eastern Standard Time (UTC - 5) the code above gives

nycDayOfYear = 42

and

nzDayOfYear = 43

It would take some work to make that calculation work across year boundaries.

Curiously, the following code:

var nzDayOfEra = nzCalendar.ordinality(of: .day, in: .era, for: now)
let nycDayOfEra = nycCalendar.ordinality(of: .day, in: .era, for: now)

Gives the same value for both NZ and NYC. I'm not sure why.

EDIT:

Ok, I did some experimenting and got code that works. What I do is to convert both dates to month/day/year date components using a calendar set to the local time zone for each time. Then I use a method dateComponents(_:from:to:) to calculate the difference between those 2 DateComponents, in days:

import UIKit

let date = Date()

guard let nycTimeZone = TimeZone(abbreviation: "EST"),
  let nzTimeZone = TimeZone(abbreviation: "NZDT") else {
    fatalError()
}
var nycCalendar = Calendar(identifier: .gregorian)
nycCalendar.timeZone = nycTimeZone
var nzCalendar = Calendar(identifier: .gregorian)
nzCalendar.timeZone = nzTimeZone

let now = Date()

let nycDateComponents = nycCalendar.dateComponents([.month, .day, .year], from: now)
let nzDateComponents = nzCalendar.dateComponents([.month, .day, .year], from: now)

let difference = Calendar.current.dateComponents([.day],
  from: nycDateComponents,
    to: nzDateComponents)

let daysDifference = difference.days

As of this writing that gives a daysDifference of 1. Since we're using the dateComponents(_:from:to:) function, it takes care of the math to calculate the number of days difference between the 2 month/day/year DateComponents.

Getting the difference between two Dates (months/days/hours/minutes/seconds) in Swift

Xcode 8.3 • Swift 3.1 or later

You can use Calendar to help you create an extension to do your date calculations as follow:

extension Date {
    /// Returns the amount of years from another date
    func years(from date: Date) -> Int {
        return Calendar.current.dateComponents([.year], from: date, to: self).year ?? 0
    }
    /// Returns the amount of months from another date
    func months(from date: Date) -> Int {
        return Calendar.current.dateComponents([.month], from: date, to: self).month ?? 0
    }
    /// Returns the amount of weeks from another date
    func weeks(from date: Date) -> Int {
        return Calendar.current.dateComponents([.weekOfMonth], from: date, to: self).weekOfMonth ?? 0
    }
    /// Returns the amount of days from another date
    func days(from date: Date) -> Int {
        return Calendar.current.dateComponents([.day], from: date, to: self).day ?? 0
    }
    /// Returns the amount of hours from another date
    func hours(from date: Date) -> Int {
        return Calendar.current.dateComponents([.hour], from: date, to: self).hour ?? 0
    }
    /// Returns the amount of minutes from another date
    func minutes(from date: Date) -> Int {
        return Calendar.current.dateComponents([.minute], from: date, to: self).minute ?? 0
    }
    /// Returns the amount of seconds from another date
    func seconds(from date: Date) -> Int {
        return Calendar.current.dateComponents([.second], from: date, to: self).second ?? 0
    }
    /// Returns the a custom time interval description from another date
    func offset(from date: Date) -> String {
        if years(from: date)   > 0 { return "\(years(from: date))y"   }
        if months(from: date)  > 0 { return "\(months(from: date))M"  }
        if weeks(from: date)   > 0 { return "\(weeks(from: date))w"   }
        if days(from: date)    > 0 { return "\(days(from: date))d"    }
        if hours(from: date)   > 0 { return "\(hours(from: date))h"   }
        if minutes(from: date) > 0 { return "\(minutes(from: date))m" }
        if seconds(from: date) > 0 { return "\(seconds(from: date))s" }
        return ""
    }
}

---

Using Date Components Formatter

let dateComponentsFormatter = DateComponentsFormatter()
dateComponentsFormatter.allowedUnits = [.second, .minute, .hour, .day, .weekOfMonth, .month, .year]
dateComponentsFormatter.maximumUnitCount = 1
dateComponentsFormatter.unitsStyle = .full
dateComponentsFormatter.string(from: Date(), to: Date(timeIntervalSinceNow: 4000000))  // "1 month"

---

let date1 = DateComponents(calendar: .current, year: 2014, month: 11, day: 28, hour: 5, minute: 9).date!
let date2 = DateComponents(calendar: .current, year: 2015, month: 8, day: 28, hour: 5, minute: 9).date!

let years = date2.years(from: date1)     // 0
let months = date2.months(from: date1)   // 9
let weeks = date2.weeks(from: date1)     // 39
let days = date2.days(from: date1)       // 273
let hours = date2.hours(from: date1)     // 6,553
let minutes = date2.minutes(from: date1) // 393,180
let seconds = date2.seconds(from: date1) // 23,590,800

let timeOffset = date2.offset(from: date1) // "9M"

let date3 = DateComponents(calendar: .current, year: 2014, month: 11, day: 28, hour: 5, minute: 9).date!
let date4 = DateComponents(calendar: .current, year: 2015, month: 11, day: 28, hour: 5, minute: 9).date!

let timeOffset2 = date4.offset(from: date3) // "1y"

let date5 = DateComponents(calendar: .current, year: 2017, month: 4, day: 28).date!
let now = Date()
let timeOffset3 = now.offset(from: date5) // "1w"

Difference between two NSDates in Months and Years in Swift iOS

You can do this in following way...

//set start & end date in correct format
let strStartDate = "September 2019"
let strEndDate = "December 2019"

//create date formatter
let formatter = DateFormatter()
formatter.dateFormat = "MMMM yyyy"

//convert string into date object
guard let startDate = formatter.date(from: strStartDate) else {
  print("invalid start date")
   return
}

 //convert string into date object
guard let endDate = formatter.date(from: strEndDate) else {
  print("invalid end date time")
  return
}

//calculate the month from end date and that should not exceed the start date
for month in 1...6 {

  if let dt = Calendar.current.date(byAdding: .month, value: -month, to: endDate) {
     if dt.compare(startDate) == .orderedAscending {
        break
      } 
      print(formatter.string(from: dt!))
  }
}

Get minutes and hours between two NSDates?

Mac OS X 10.10 Yosemite introduces the smart NSDateComponentsFormatter to display time intervals in components like 18h 56m 4s

This result of this snippet is the formatted time interval from midnight until now.

let calendar = NSCalendar.currentCalendar()
let midnight = calendar.startOfDayForDate(NSDate())
let timeinterval = NSDate().timeIntervalSinceDate(midnight)

let formatter = NSDateComponentsFormatter()
formatter.unitsStyle = .Abbreviated
formatter.stringFromTimeInterval(timeinterval)

Find difference in seconds between NSDates as integer using Swift

Your attempt to calculate elapsedTime is incorrect. In Swift 3, it would be:

let elapsed = Date().timeIntervalSince(timeAtPress)

Note the () after the Date reference. The Date() instantiates a new date object, and then timeIntervalSince returns the time difference between that and timeAtPress. That will return a floating point value (technically, a TimeInterval).

If you want that as truncated to a Int value, you can just use:

let duration = Int(elapsed)

And, BTW, your definition of the timeAtPress variable doesn't need to instantiate a Date object. I presume you intended:

var timeAtPress: Date!

That defines the variable as a Date variable (an implicitly unwrapped one), but you'd presumably defer the actual instantiation of that variable until pressed is called.

---

Alternatively, I often use CFAbsoluteTimeGetCurrent(), e.g.,

var start: CFAbsoluteTime!

And when I want to set startTime, I do the following:

start = CFAbsoluteTimeGetCurrent()

And when I want to calculate the number of seconds elapsed, I do the following:

let elapsed = CFAbsoluteTimeGetCurrent() - start

---

It's worth noting that the CFAbsoluteTimeGetCurrent documentation warns us:

Repeated calls to this function do not guarantee monotonically increasing results. The system time may decrease due to synchronization with external time references or due to an explicit user change of the clock.

This means that if you're unfortunate enough to measure elapsed time when one of these adjustments take place, you can end up with incorrect elapsed time calculation. This is true for NSDate/Date calculations too. It's safest to use a mach_absolute_time based calculation (most easily done with CACurrentMediaTime):

let start = CACurrentMediaTime()

and

let elapsed = CACurrentMediaTime() - start

This uses mach_absolute_time, but avoids some of its complexities outlined in Technical Q&A QA1398.

Remember, though, that CACurrentMediaTime/mach_absolute_time will be reset when the device is rebooted. So, bottom line, if you need accurate elapsed time calculations while an app is running, use CACurrentMediaTime. But if you're going to save this start time in persistent storage which you might recall when the app is restarted at some future date, then you have to use Date or CFAbsoluteTimeGetCurrent, and just live with any inaccuracies that may entail.

Calculate the difference between two dates. Swift 1.2

To calculate the endtime you can use

timerEndTime = NSDate(timeIntervalSinceNow:NSTimeInterval(oreWanted * 11))

So you get a NSDate object. Now you can fire a UILocalNotification at that calculated time:

Note: You need to ask for notification permissions when your app starts up. I have simplified this here with notificationsAllowed and soundsAllowed which are boolean variables in my AppDelegate.

let appDelegate = UIApplication.sharedApplication.delegate as! AppDelegate

if appDelegate.notificationsAllowed {
    let notification = UILocalNotification()
    notification.fireDate = timerEndTime
    notification.timeZone = NSTimeZone.defaultTimeZone()
    notification.alertBody = "Notification body text"
    notification.alertTitle = "Notification alert title"

    if appDelegate.soundsAllowed {
        notification.soundName = UILocalNotificationDefaultSoundName
    }

    UIApplication.sharedApplication().scheduleLocalNotification(notification)
}

---

EDIT

Register the app for notifications in AppDelegate:

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    var notificationsAllowed = false
    var notificationSoundAllowed = false

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        let notificationSettings = UIUserNotificationSettings(forTypes: UIUserNotificationType.Sound | UIUserNotificationType.Alert, categories: nil)
        UIApplication.sharedApplication().registerUserNotificationSettings(notificationSettings)

        return true
    }

    func application(application: UIApplication, didRegisterUserNotificationSettings notificationSettings: UIUserNotificationSettings) {
        if notificationSettings.types & UIUserNotificationType.Alert != nil {
            self.notificationsAllowed = true
        }

        if notificationSettings.types & UIUserNotificationType.Sound != nil {
            self.notificationSoundAllowed = true
        }
}

---

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