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?
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)
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
}
in Swift 3,4 you should use "Compare". for example:
DateArray.sort { (($0)?.compare($1))! == .orderedDescending }
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.
Another way to do it:
switch date1.compare(date2) {
case .orderedAscending:
break
case .orderedDescending:
break;
case .orderedSame:
break
}
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)")
}
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.
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: ", ")
}
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
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
}
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)
Look this http://iswift.org/cookbook/compare-2-dates
Get Dates:
// Get current date
let dateA = NSDate()
// Get a later date (after a couple of milliseconds)
let dateB = NSDate()
Using SWITCH Statement
// Compare them
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")
}
using IF Statement
if dateA.compare(dateB) == .orderedAscending {
datePickerTo.date = datePicker.date
}
//OR
if case .orderedAcending = dateA.compare(dateB) {
}
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.
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)
}
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) }
Source: Stackoverflow.com