NSDate Comparison using Swift
SwiftNsdateXcode6Swift Problem Overview
I am working on an app the requires checking the due date for homework. I want to know if a due date is within the next week, and if it is then perform an action.
Most of the documentation I could find is in Objective-C and I can't figure out how to do it in Swift.
Thanks for the help!!
Swift Solutions
Solution 1 - Swift
If you want to support ==
, <
, >
, <=
, or >=
for NSDate
s, you just have to declare this somewhere:
public func ==(lhs: NSDate, rhs: NSDate) -> Bool {
return lhs === rhs || lhs.compare(rhs) == .OrderedSame
}
public func <(lhs: NSDate, rhs: NSDate) -> Bool {
return lhs.compare(rhs) == .OrderedAscending
}
extension NSDate: Comparable { }
Solution 2 - Swift
I like using extensions to make code more readable. Here are a few NSDate extensions that can help clean your code up and make it easy to understand. I put this in a sharedCode.swift file:
extension NSDate {
func isGreaterThanDate(dateToCompare: NSDate) -> Bool {
//Declare Variables
var isGreater = false
//Compare Values
if self.compare(dateToCompare as Date) == ComparisonResult.orderedDescending {
isGreater = true
}
//Return Result
return isGreater
}
func isLessThanDate(dateToCompare: NSDate) -> Bool {
//Declare Variables
var isLess = false
//Compare Values
if self.compare(dateToCompare as Date) == ComparisonResult.orderedAscending {
isLess = true
}
//Return Result
return isLess
}
func equalToDate(dateToCompare: NSDate) -> Bool {
//Declare Variables
var isEqualTo = false
//Compare Values
if self.compare(dateToCompare as Date) == ComparisonResult.orderedSame {
isEqualTo = true
}
//Return Result
return isEqualTo
}
func addDays(daysToAdd: Int) -> NSDate {
let secondsInDays: TimeInterval = Double(daysToAdd) * 60 * 60 * 24
let dateWithDaysAdded: NSDate = self.addingTimeInterval(secondsInDays)
//Return Result
return dateWithDaysAdded
}
func addHours(hoursToAdd: Int) -> NSDate {
let secondsInHours: TimeInterval = Double(hoursToAdd) * 60 * 60
let dateWithHoursAdded: NSDate = self.addingTimeInterval(secondsInHours)
//Return Result
return dateWithHoursAdded
}
}
Now if you can do something like this:
//Get Current Date/Time
var currentDateTime = NSDate()
//Get Reminder Date (which is Due date minus 7 days lets say)
var reminderDate = dueDate.addDays(-7)
//Check if reminderDate is Greater than Right now
if(reminderDate.isGreaterThanDate(currentDateTime)) {
//Do Something...
}
Solution 3 - Swift
This is how you compare two NSDates in Swift, I just tested it in Xcode's playground:
if date1.compare(date2) == NSComparisonResult.OrderedDescending
{
NSLog("date1 after date2");
} else if date1.compare(date2) == NSComparisonResult.OrderedAscending
{
NSLog("date1 before date2");
} else
{
NSLog("dates are equal");
}
So to check if a date dueDate
is within a week from now:
let dueDate=...
let calendar = NSCalendar.currentCalendar()
let comps = NSDateComponents()
comps.day = 7
let date2 = calendar.dateByAddingComponents(comps, toDate: NSDate(), options: NSCalendarOptions.allZeros)
if dueDate.compare(date2!) == NSComparisonResult.OrderedDescending
{
NSLog("not due within a week");
} else if dueDate.compare(date2!) == NSComparisonResult.OrderedAscending
{
NSLog("due within a week");
} else
{
NSLog("due in exactly a week (to the second, this will rarely happen in practice)");
}
Solution 4 - Swift
I always did it in one line:
let greater = date1.timeIntervalSince1970 < date2.timeIntervalSince1970
Still readable in the if
block
Solution 5 - Swift
In Swift3, the Date
struct in the Foundation
now implements the Comparable
protocol. So, the previous Swift2 NSDate
approaches are superceded by Swift3 Date
.
/**
`Date` represents a single point in time.
A `Date` is independent of a particular calendar or time zone. To represent a `Date` to a user, you must interpret it in the context of a `Calendar`.
*/
public struct Date : ReferenceConvertible, Comparable, Equatable {
// .... more
/**
Returns the interval between the receiver and another given date.
- Parameter another: The date with which to compare the receiver.
- Returns: The interval between the receiver and the `another` parameter. If the receiver is earlier than `anotherDate`, the return value is negative. If `anotherDate` is `nil`, the results are undefined.
- SeeAlso: `timeIntervalSince1970`
- SeeAlso: `timeIntervalSinceNow`
- SeeAlso: `timeIntervalSinceReferenceDate`
*/
public func timeIntervalSince(_ date: Date) -> TimeInterval
// .... more
/// Returns true if the two `Date` values represent the same point in time.
public static func ==(lhs: Date, rhs: Date) -> Bool
/// Returns true if the left hand `Date` is earlier in time than the right hand `Date`.
public static func <(lhs: Date, rhs: Date) -> Bool
/// Returns true if the left hand `Date` is later in time than the right hand `Date`.
public static func >(lhs: Date, rhs: Date) -> Bool
/// Returns a `Date` with a specified amount of time added to it.
public static func +(lhs: Date, rhs: TimeInterval) -> Date
/// Returns a `Date` with a specified amount of time subtracted from it.
public static func -(lhs: Date, rhs: TimeInterval) -> Date
// .... more
}
Note ...
In Swift3, Date
is struct
, it means that it is value type
. NSDate
is class
, it is reference type
.
// Swift3
let a = Date()
let b = a //< `b` will copy `a`.
// So, the addresses between `a` and `b` are different.
// `Date` is some kind different with `NSDate`.
Solution 6 - Swift
extension NSDate {
// MARK: - Dates comparison
func isGreaterThanDate(dateToCompare: NSDate) -> Bool {
return self.compare(dateToCompare) == NSComparisonResult.OrderedDescending
}
func isLessThanDate(dateToCompare: NSDate) -> Bool {
return self.compare(dateToCompare) == NSComparisonResult.OrderedAscending
}
func equalToDate(dateToCompare: NSDate) -> Bool {
return self.compare(dateToCompare) == NSComparisonResult.OrderedSame
}
}
Solution 7 - Swift
If you want to compare dates with granularity (just same day or year etc) on swift 3.
func compareDate(date1:NSDate, date2:NSDate, toUnitGranularity: NSCalendar.Unit) -> Bool {
let order = NSCalendar.current.compare(date1 as Date, to: date2 as Date, toGranularity: .day)
switch order {
case .orderedSame:
return true
default:
return false
}
}
For other calendar comparisons change .day to;
.year .month .day .hour .minute .second
Solution 8 - Swift
Swift already implement Date comparison just use date1 > date2 and so on.
/// Returns true if the two `Date` values represent the same point in time.
public static func ==(lhs: Date, rhs: Date) -> Bool
/// Returns true if the left hand `Date` is earlier in time than the right hand `Date`.
public static func <(lhs: Date, rhs: Date) -> Bool
/// Returns true if the left hand `Date` is later in time than the right hand `Date`.
public static func >(lhs: Date, rhs: Date) -> Bool
/// Returns a `Date` with a specified amount of time added to it.
public static func +(lhs: Date, rhs: TimeInterval) -> Date
/// Returns a `Date` with a specified amount of time subtracted from it.
public static func -(lhs: Date, rhs: TimeInterval) -> Date
/// Add a `TimeInterval` to a `Date`.
///
/// - warning: This only adjusts an absolute value. If you wish to add calendrical concepts like hours, days, months then you must use a `Calendar`. That will take into account complexities like daylight saving time, months with different numbers of days, and more.
public static func +=(lhs: inout Date, rhs: TimeInterval)
/// Subtract a `TimeInterval` from a `Date`.
///
/// - warning: This only adjusts an absolute value. If you wish to add calendrical concepts like hours, days, months then you must use a `Calendar`. That will take into account complexities like daylight saving time, months with different numbers of days, and more.
public static func -=(lhs: inout Date, rhs: TimeInterval)
Solution 9 - Swift
in Swift 3, Date is Comparable so we can directly compare dates like
let date1 = Date()
let date2 = Date()
let isGreater = date1 > date2
print(isGreater)
let isEqual = date1 == date2
print(isEqual)
or alternatively
let result = date1.compare(date2)
switch result {
case .OrderedAscending : print("date 1 is earlier than date 2")
case .OrderedDescending : print("date 1 is later than date 2")
case .OrderedSame : print("two dates are the same")
}
better way creating extension
on Date
extension Date {
fun isGreater(than date: Date) -> Bool {
return self > date
}
func isSmaller(than date: Date) -> Bool {
return self < date
}
func isEqual(to date: Date) -> Bool {
return self == date
}
}
usage let isGreater = date1.isGreater(than: date2)
Solution 10 - Swift
This function worked for me for comparing whether one date (startDate) was after the endDate where both were defined as NSDate variables:
if startDate.compare(endDate as Date) == ComparisonResult.orderedDescending
Solution 11 - Swift
implementation in Swift
let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as NSString
let files = NSFileManager.defaultManager().contentsOfDirectoryAtPath(documentsPath, error: nil)
let filesAndProperties = NSMutableArray()
for file in files! {
let filePath = documentsPath.stringByAppendingString(file as NSString)
let properties = NSFileManager.defaultManager().attributesOfItemAtPath(filePath, error: nil)
let modDate = properties![NSFileModificationDate] as NSDate
filesAndProperties.addObject(NSDictionary(objectsAndKeys: file, "path", modDate, "lastModDate"))
}
let sortedFiles = filesAndProperties.sortedArrayUsingComparator({
(path1, path2) -> NSComparisonResult in
var comp = (path1.objectForKey("lastModDate") as NSDate).compare(path2.objectForKey("lastModDate") as NSDate)
if comp == .OrderedDescending {
comp = .OrderedAscending
} else if comp == .OrderedAscending {
comp = .OrderedDescending
}
return comp
})
Solution 12 - Swift
var dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let dateData: String = dateFormatter.stringFromDate(date1)
let testDate: String = dateFormatter.stringFromDate(date2)
print(dateData == testDate)
Solution 13 - Swift
someArray.sort({($0.dateAdded?.timeIntervalSinceReferenceDate)! < ($1.dateAdded?.timeIntervalSinceReferenceDate)!})
dateAdded is an NSDate variable in my object
class MyClass {
let dateAdded: NSDate?
}
Solution 14 - Swift
We have scenario to check current time lies b/w two times (two dates).For Example , I want to check the current lie between clinic(Hospital) opening time and closing time.
Use the simple Code.
NSDate * now = [NSDate date];
NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
[outputFormatter setDateFormat:@"HH:mm:ss"];
//current time
NSString *currentTimeString = [outputFormatter stringFromDate:now];
NSDate *dateCurrent = [outputFormatter dateFromString:currentTimeString];
NSString *timeStart = @"09:00:00";
NSString *timeEnd = @"22:00:00";
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"HH:mm:ss"];
NSDate *dateStart= [formatter timeStart];
NSDate *dateEnd = [formatter timeEnd];
NSComparisonResult result = [dateCurrent compare:dateStart];
NSComparisonResult resultSecond = [date2 compare:dateEnd];
if(result == NSOrderedDescending && resultSecond == NSOrderedDescending)
{
NSLog(@"current time lies in starting and end time");
}else {
NSLog(@"current time doesn't lie in starting and end time");
}
Solution 15 - Swift
For swift 3, you can use the below function to compare between two dates.
func compareDate(dateInitial:Date, dateFinal:Date) -> Bool {
let order = Calendar.current.compare(dateInitial, to: dateFinal, toGranularity: .day)
switch order {
case .orderedSame:
return true
default:
return false
}
}
toGranularity can be changed according to the constraints on which you want to apply your comparison.
Solution 16 - Swift
To extend on SashaZ - Swift iOS 8 and up
- Are these dates from the same day?
- Are these dates from the same month?
- is this date from a previous month than the other?
When you need more than simply bigger or smaller date comparisons. For example is it the same day or the previous day,...
Note: Never forget the timezone. Calendar timezone has a default, but if you do not like the default, you have to set the timezone yourself. To know which day it is, you need to know in which timezone you are asking.
extension Date {
func compareTo(date: Date, toGranularity: Calendar.Component ) -> ComparisonResult {
var cal = Calendar.current
cal.timeZone = TimeZone(identifier: "Europe/Paris")!
return cal.compare(self, to: date, toGranularity: toGranularity)
}
}
Use it like this:
if thisDate.compareTo(date: Date(), toGranularity: .day) == .orderedDescending {
// thisDate is a previous day
}
Of a more complex example. Find and filter all dates in an array, which are from the same day as "findThisDay":
let formatter = DateFormatter()
formatter.timeZone = TimeZone(identifier: "Europe/Paris")
formatter.dateFormat = "yyyy/MM/dd HH:mm:ss"
let findThisDay = formatter.date(from: "2018/11/05 08:11:08")!
_ = [
formatter.date(from: "2018/12/05 08:08:08")!,
formatter.date(from: "2018/11/05 08:11:08")!,
formatter.date(from: "2018/11/05 11:08:22")!,
formatter.date(from: "2018/11/05 22:08:22")!,
formatter.date(from: "2018/11/05 08:08:22")!,
formatter.date(from: "2018/11/07 08:08:22")!,
]
.filter{ findThisDay.compareTo(date: $0 , toGranularity: .day) == .orderedSame }
.map { print(formatter.string(from: $0)) }