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

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.

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#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)

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#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")