Example
There are 4 methods for comparing dates:
Swift
isEqualToDate(anotherDate: NSDate) -> BoolearlierDate(anotherDate: NSDate) -> NSDatelaterDate(anotherDate: NSDate) -> NSDatecompare(anotherDate: NSDate) -> NSComparisonResult
Objective-C
- (BOOL)isEqualToDate:(NSDate *)anotherDate- (NSDate *)earlierDate:(NSDate *)anotherDate- (NSDate *)laterDate:(NSDate *)anotherDate- (NSComparisonResult)compare:(NSDate *)anotherDate
Let's say we have 2 dates:
Swift
let date1: NSDate = ... // initialized as July 7, 2016 00:00:00
let date2: NSDate = ... // initialized as July 2, 2016 00:00:00
Objective-C
NSDate *date1 = ... // initialized as July 7, 2016 00:00:00
NSDate *date2 = ... // initialized as July 2, 2016 00:00:00
Then, to compare them, we try this code:
Swift
if date1.isEqualToDate(date2) {
// returns false, as both dates aren't equal
}
earlierDate: NSDate = date1.earlierDate(date2) // returns the earlier date of the two (date 2)
laterDate: NSDate = date1.laterDate(date2) // returns the later date of the two (date1)
result: NSComparisonResult = date1.compare(date2)
if result == .OrderedAscending {
// true if date1 is earlier than date2
} else if result == .OrderedSame {
// true if the dates are the same
} else if result == .OrderedDescending {
// true if date1 is later than date1
}
Objective-C
if ([date1 isEqualToDate:date2]) {
// returns false, as both date are not equal
}
NSDate *earlierDate = [date1 earlierDate:date2]; // returns date which comes earlier from both date, here it will return date2
NSDate *laterDate = [date1 laterDate:date2]; // returns date which comes later from both date, here it will return date1
NSComparisonResult result = [date1 compare:date2];
if (result == NSOrderedAscending) {
// fails
// comes here if date1 is earlier then date2, in our case it will not come here
} else if (result == NSOrderedSame){
// fails
// comes here if date1 is same as date2, in our case it will not come here
} else{ // NSOrderedDescending
// succeeds
// comes here if date1 is later than date2, in our case it will come here
}
If you want to compare dates and handle seconds, weeks, months and years:
Swift 3
let dateStringUTC = "2016-10-22 12:37:48 +0000"
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_US_POSIX")
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss X"
let date = dateFormatter.date(from: dateStringUTC)!
let now = Date()
let formatter = DateComponentsFormatter()
formatter.unitsStyle = .full
formatter.maximumUnitCount = 2
let string = formatter.string(from: date, to: Date())! + " " + NSLocalizedString("ago", comment: "added after elapsed time to say how long before")
Or you can use this for each component:
// get the current date and time
let currentDateTime = Date()
// get the user's calendar
let userCalendar = Calendar.current
// choose which date and time components are needed
let requestedComponents: Set<Calendar.Component> = [
.year,
.month,
.day,
.hour,
.minute,
.second
]
// get the components
let dateTimeComponents = userCalendar.dateComponents(requestedComponents, from: currentDateTime)
// now the components are available
dateTimeComponents.year
dateTimeComponents.month
dateTimeComponents.day
dateTimeComponents.hour
dateTimeComponents.minute
dateTimeComponents.second
