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