Swift 3 - Comparing Date objects - ios

Question

I'm updating my app to Swift 3.0 syntax (I know it's still in beta but I want to be prepared as soon as it released).
Until the previous Beta of Xcode (Beta 5) I was able to compare two Date objects using the operands <, > and ==. But in the latest beta (Beta 6) this isn't working any more. Here are some screenshots:
As you can see in both screenshots, these are two Date objects. But I get the following error:
What am I doing wrong? The functions are still declared in the Date class:
static func >(Date, Date)
Returns true if the left hand Date is later in time than the right hand Date.
Is this just a Beta bug or am I doing something wrong?

Answer 1

I have tried this snippet (in Xcode 8 Beta 6), and it is working fine.
let date1 = Date()
let date2 = Date().addingTimeInterval(100)
if date1 == date2 { ... }
else if date1 > date2 { ... }
else if date1 < date2 { ... }

Answer 2

Date is Comparable & Equatable (as of Swift 3)
This answer complements #Ankit Thakur's answer.
Since Swift 3 the Date struct (based on the underlying NSDate class) adopts the Comparable and Equatable protocols.
Comparable requires that Date implement the operators: <, <=, >, >=.
Equatable requires that Date implement the == operator.
Equatable allows Date to use the default implementation of the != operator (which is the inverse of the Equatable == operator implementation).
The following sample code exercises these comparison operators and confirms which comparisons are true with print statements.
Comparison function
import Foundation
func describeComparison(date1: Date, date2: Date) -> String {
var descriptionArray: [String] = []
if date1 < date2 {
descriptionArray.append("date1 < date2")
}
if date1 <= date2 {
descriptionArray.append("date1 <= date2")
}
if date1 > date2 {
descriptionArray.append("date1 > date2")
}
if date1 >= date2 {
descriptionArray.append("date1 >= date2")
}
if date1 == date2 {
descriptionArray.append("date1 == date2")
}
if date1 != date2 {
descriptionArray.append("date1 != date2")
}
return descriptionArray.joined(separator: ", ")
}
Sample Use
let now = Date()
describeComparison(date1: now, date2: now.addingTimeInterval(1))
// date1 < date2, date1 <= date2, date1 != date2
describeComparison(date1: now, date2: now.addingTimeInterval(-1))
// date1 > date2, date1 >= date2, date1 != date2
describeComparison(date1: now, date2: now)
// date1 <= date2, date1 >= date2, date1 == date2

Answer 3

from Swift 3 and above, Date is Comparable so we can directly compare dates like
let date1 = Date()
let date2 = Date().addingTimeInterval(50)
let isGreater = date1 > date2
print(isGreater)
let isSmaller = date1 < date2
print(isSmaller)
let isEqual = date1 == date2
print(isEqual)
Alternatively We can create extension on Date
extension Date {
func isEqualTo(_ date: Date) -> Bool {
return self == date
}
func isGreaterThan(_ date: Date) -> Bool {
return self > date
}
func isSmallerThan(_ date: Date) -> Bool {
return self < date
}
}
Use: let isEqual = date1.isEqualTo(date2)

Answer 4

Don't use comparators <, >, ==, !=.
Use compare(_ other: Date) function.
Usage
// Get current date
let dateA = Date()
// Get a later date (after a couple of milliseconds)
let dateB = Date()
// Compare them using switch
switch dateA.compare(dateB) {
case .orderedAscending : print("Date A is earlier than date B")
case .orderedDescending : print("Date A is later than date B")
case .orderedSame : print("The two dates are the same")
}
// Compare them using if
if dateA.compare(dateB) == .orderedAscending {
datePickerTo.date = datePicker.date
}

Answer 5

For me the problem was that I had my own extension to Date class that was defining all the compare operators. Now (since swift 3) that Date is comparable, these extensions are not needed. So I commented them out and it worked.

Answer 6

SWIFT 3: Don't know if this is what you're looking for. But I compare a string to a current timestamp to see if my string is older that now.
func checkTimeStamp(date: String!) -> Bool {
let dateFormatter: DateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
dateFormatter.locale = Locale(identifier:"en_US_POSIX")
let datecomponents = dateFormatter.date(from: date)
let now = Date()
if (datecomponents! >= now) {
return true
} else {
return false
}
}
To use it:
if (checkTimeStamp(date:"2016-11-21 12:00:00") == false) {
// Do something
}

Answer 7

If you want to ignore seconds for example
you can use
func isDate(Date, equalTo: Date, toUnitGranularity: NSCalendar.Unit) -> Bool
Example compare if it's the same day:
Calendar.current.isDate(date1, equalTo: date2, toGranularity: .day)

Answer 8

To compare date only with year - month - day and without time for me worked like this:
let order = Calendar.current.compare(self.startDate, to: compareDate!, toGranularity: .day)
switch order {
case .orderedAscending:
print("\(gpsDate) is after \(self.startDate)")
case .orderedDescending:
print("\(gpsDate) is before \(self.startDate)")
default:
print("\(gpsDate) is the same as \(self.startDate)")
}

Answer 9

As of the time of this writing, Swift natively supports comparing Dates with all comparison operators (i.e. <, <=, ==, >=, and >). You can also compare optional Dates but are limited to <, ==, and >. If you need to compare two optional dates using <= or >=, i.e.
let date1: Date? = ...
let date2: Date? = ...
if date1 >= date2 { ... }
You can overload the <= and >=operators to support optionals:
func <= <T: Comparable>(lhs: T?, rhs: T?) -> Bool {
return lhs == rhs || lhs < rhs
}
func >= <T: Comparable>(lhs: T?, rhs: T?) -> Bool {
return lhs == rhs || lhs > rhs
}

Answer 10

extension Date {
func isBetween(_ date1: Date, and date2: Date) -> Bool {
return (min(date1, date2) ... max(date1, date2)).contains(self)
}
}
let resultArray = dateArray.filter { $0.dateObj!.isBetween(startDate, and: endDate) }

Answer 11

Another way to do it:
switch date1.compare(date2) {
case .orderedAscending:
break
case .orderedDescending:
break;
case .orderedSame:
break
}

Answer 12

var strDateValidate = ""
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let firstDate = dateFormatter.date(from:lblStartTime.text!)
let secondDate = dateFormatter.date(from:lblEndTime.text!)
if firstDate?.compare(secondDate!) == .orderedSame || firstDate?.compare(secondDate!) == .orderedAscending {
print("Both dates are same or first is less than scecond")
strDateValidate = "yes"
}
else
{
//second date is bigger than first
strDateValidate = "no"
}
if strDateValidate == "no"
{
alertView(message: "Start date and end date for a booking must be equal or Start date must be smaller than the end date", controller: self)
}

Answer 13

Swift 5:
1) If you use Date type:
let firstDate = Date()
let secondDate = Date()
print(firstDate > secondDate)
print(firstDate < secondDate)
print(firstDate == secondDate)
2) If you use String type:
let firstStringDate = "2019-05-22T09:56:00.1111111"
let secondStringDate = "2019-05-22T09:56:00.2222222"
print(firstStringDate > secondStringDate) // false
print(firstStringDate < secondStringDate) // true
print(firstStringDate == secondStringDate) // false
I'm not sure or the second option works at 100%. But how much would I not change the values of firstStringDate and secondStringDate the result was correct.

Answer 14

in Swift 3,4 you should use "Compare".
for example:
DateArray.sort { (($0)?.compare($1))! == .orderedDescending }