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Compare Dates

Date comparison is available both via simple math operators (<,>,<=,>=) or throught several other functions which allows a more fined grained control of the comparison.

4.0 - Compare Dates

Standard comparison between dates can be done using the classic .compare() functions or mathematical operators. SwiftDate also introduces two additional convenience methods:

  • isBeforeDate(_:orEqual:granularity:) Compares whether the receiver is before/before equal date based on their components down to a given unit granularity.
  • isAfterDate(_:orEqual:granularity:) Compares whether the receiver is after date based on their components down to a given unit granularity.

4.1 - Extended Comparison with Presets

While standard comparison between two dates can be done by using mathematical operators, extended comparison is made via .compare() method which offer more than 25+ different types of relevant comparisons.

func compare(_ compareType: DateComparisonType) -> Bool

takes only one argument:

  • compareType | DateComparisonType: the type of comparison to make

DateComparisonType is an enum which defines the type of comparison to make. This is the actual list of compare functions you can use:

For Days

  • isToday
  • isTomorrow
  • isYesterday
  • isSameDay(_ : DateRepresentable)

For Weeks

  • isThisWeek
  • isNextWeek
  • isLastWeek
  • isSameWeek(_: DateRepresentable)

For Months

  • isThisMonth
  • isNextMonth
  • isLastMonth
  • isSameMonth(_: DateRepresentable)

For Years

  • isThisYear
  • isNextYear
  • isLastYear
  • isSameYear(_: DateRepresentable)

For Relative Time

  • isInTheFuture
  • isInThePast
  • isEarlier(than: DateRepresentable)
  • isLater(than: DateRepresentable)
  • isWeekday
  • isWeekend

For Day Time

  • isMorning
  • isAfternoon
  • isEvening
  • isNight

For TZ

  • isInDST

CONTRIBUTE! Have you a new related date you want to be part of this list? Create a new PR with the code and unit tests and we'll be happy to add it to the list!

Examples:

// return false
let _ = DateInRegion().dateAt(.endOfDay).compare(.isTomorrow)
// return true
let _ = DateInRegion() + 7.days).compare(.isNextWeek)
// return true
let _ = DateInRegion().dateAt(.startOfWeek) - 1.days).compare(.isLastWeek)

4.2 - Comparison with Granularity

A more fined grained control for dates comparison can be obtained using the .compare(toDate:granularity:) function which offers to return a ComparisonResult value that indicates the ordering of two given dates based on their components down to a given unit granularity.

func compare(toDate refDate: DateInRegion, granularity: Calendar.Component) -> ComparisonResult

takes two arguments:

  • refDate | DateInRegion: date to compare against to.
  • granularity | Calendar.Component: The smallest unit that must, along with all larger units, be less for the given dates

Example:



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4.3 - Check if Date is Close to Another


Decides whether a Date is "close by" another one passed in parameter, where "Being close" is measured using a precision argument which is initialized with a 300 second interval (5 minute) or a specified interval.


The function is called .compareCloseTo(_:precision:) and takes two arguments:


    

  • refDate | DateInRegion reference date compare against to
    • 

  • precision | TimeInterval The precision of the comparison.
    • 



Examples:


let date = DateInRegion("2015-01-01 04:00:00", format: dateFormat, region: regionRome)!
let refDate = DateInRegion("2015-01-01 00:00:00", format: dateFormat, region: regionRome)!
// return true because prevision is set to 5 hours and date differs for only 4 hours
let _ = dateC.compareCloseTo(refDate, precision: 5.hours.timeInterval)



4.4 - Check if Date is Inside another


Compares equality of two given dates based on their components down to a given unit granularity.


The function is called .isInside(date:granularity:) and takes two arguments:


    

  • date: date to compare
    • 

  • granularity: The smallest unit that must, along with all larger units, be equal for the given dates to be considered the same.
    • 




4.5 - Check if Date is Inside a Range


Using .isInRange() function you can check if a given date is inside the range between two dates.


func isInRange(date startDate: Date, and endDate: Date, orEqual: Bool = false, granularity: Calendar.Component = .nanosecond) -> Bool


takes 4 arguments:


    

  • startDate: the lower bound limit of the range
    • 

  • endDate: the upper bound limit of the range
    • 

  • orEqualt: true to also validate the equality
    • 

  • granularity: smallest unit that must, along with all larger units, be greater for the given dates
    • 



Example:


let lowerBound = DateInRegion("2018-05-31 23:00:00", format: dateFormat, region: regionRome)!
let upperBound = DateInRegion("2018-06-01 01:00:00", format: dateFormat, region: regionRome)!

let testDate = DateInRegion("2018-06-01 00:02:00", format: dateFormat, region: regionRome)!
// return true, date is inside the hour granularity
let _ = testDate.isInRange(date: lowerBound, and: upperBound, orEqual: true, granularity: .hour)


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Next Chapter: Date Formatting