How can I calculate the difference between two dates?

Question

How can I calculate the days between 1 Jan 2010 and (for example) 3 Feb 2010?

Answer 1

NSDate *date1 = [NSDate dateWithString:@"2010-01-01 00:00:00 +0000"];
NSDate *date2 = [NSDate dateWithString:@"2010-02-03 00:00:00 +0000"];

NSTimeInterval secondsBetween = [date2 timeIntervalSinceDate:date1];

int numberOfDays = secondsBetween / 86400;

NSLog(@"There are %d days in between the two dates.", numberOfDays);

EDIT:

Remember, NSDate objects represent exact moments of time, they do not have any associated time-zone information. When you convert a string to a date using e.g. an NSDateFormatter, the NSDateFormatter converts the time from the configured timezone. Therefore, the number of seconds between two NSDate objects will always be time-zone-agnostic.

Furthermore, this documentation specifies that Cocoa's implementation of time does not account for leap seconds, so if you require such accuracy, you will need to roll your own implementation.

Answer 2

You may want to use something like this:

NSDateComponents *components;
NSInteger days;

components = [[NSCalendar currentCalendar] components: NSDayCalendarUnit 
        fromDate: startDate toDate: endDate options: 0];
days = [components day];

I believe this method accounts for situations such as dates that span a change in daylight savings.

Answer 3

NSTimeInterval diff = [date2 timeIntervalSinceDate:date1]; // in seconds

where date1 and date2 are NSDate's.

Also, note the definition of NSTimeInterval:

typedef double NSTimeInterval;

Answer 4

Checkout this out. It takes care of daylight saving , leap year as it used iOS calendar to calculate.You can change the string and conditions to includes minutes with hours and days.

+(NSString*)remaningTime:(NSDate*)startDate endDate:(NSDate*)endDate
{
    NSDateComponents *components;
    NSInteger days;
    NSInteger hour;
    NSInteger minutes;
    NSString *durationString;

    components = [[NSCalendar currentCalendar] components: NSCalendarUnitDay|NSCalendarUnitHour|NSCalendarUnitMinute fromDate: startDate toDate: endDate options: 0];

    days = [components day];
    hour = [components hour];
    minutes = [components minute];

    if(days>0)
    {
        if(days>1)
            durationString=[NSString stringWithFormat:@"%d days",days];
        else
            durationString=[NSString stringWithFormat:@"%d day",days];
        return durationString;
    }
    if(hour>0)
    {        
        if(hour>1)
            durationString=[NSString stringWithFormat:@"%d hours",hour];
        else
            durationString=[NSString stringWithFormat:@"%d hour",hour];
        return durationString;
    }
    if(minutes>0)
    {
        if(minutes>1)
            durationString = [NSString stringWithFormat:@"%d minutes",minutes];
        else
            durationString = [NSString stringWithFormat:@"%d minute",minutes];

        return durationString;
    }
    return @""; 
}

Answer 5

With Swift 5 and iOS 12, according to your needs, you may use one of the two following ways to find the difference between two dates in days.

---

#1. Using Calendar's dateComponents(_:from:to:) method

import Foundation

let calendar = Calendar.current

let startDate = calendar.date(from: DateComponents(year: 2010, month: 11, day: 22))!
let endDate = calendar.date(from: DateComponents(year: 2015, month: 5, day: 1))!

let dateComponents = calendar.dateComponents([Calendar.Component.day], from: startDate, to: endDate)

print(dateComponents) // prints: day: 1621 isLeapMonth: false
print(String(describing: dateComponents.day)) // prints: Optional(1621)

---

#2. Using DateComponentsFormatter's string(from:to:) method

import Foundation

let calendar = Calendar.current

let startDate = calendar.date(from: DateComponents(year: 2010, month: 11, day: 22))!
let endDate = calendar.date(from: DateComponents(year: 2015, month: 5, day: 1))!

let formatter = DateComponentsFormatter()
formatter.unitsStyle = .full
formatter.allowedUnits = [NSCalendar.Unit.day]

let elapsedTime = formatter.string(from: startDate, to: endDate)
print(String(describing: elapsedTime)) // prints: Optional("1,621 days")

Answer 6

Swift 4
Try this and see (date range with String):

// Start & End date string
let startingAt = "01/01/2018"
let endingAt = "08/03/2018"

// Sample date formatter
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd/MM/yyyy"

// start and end date object from string dates
var startDate = dateFormatter.date(from: startingAt) ?? Date()
let endDate = dateFormatter.date(from: endingAt) ?? Date()


// Actual operational logic
var dateRange: [String] = []
while startDate <= endDate {
    let stringDate = dateFormatter.string(from: startDate)
    startDate = Calendar.current.date(byAdding: .day, value: 1, to: startDate) ?? Date()
    dateRange.append(stringDate)
}

print("Resulting Array - \(dateRange)")

Swift 3

var date1 = Date(string: "2010-01-01 00:00:00 +0000")
var date2 = Date(string: "2010-02-03 00:00:00 +0000")
var secondsBetween: TimeInterval = date2.timeIntervalSince(date1)
var numberOfDays: Int = secondsBetween / 86400
print(numberOfDays)

Answer 7

You can find the difference by converting the date in seconds and take time interval since 1970 for this and then you can find the difference between two dates.