How to sort an array of dates in descending order

Question

I have a NSDictionary that parsed to an array one of the element is date, i tried using [startimeArray sortUsingSelector:@selector(compare:)]; (starttimeArray) is my date but it only arrange ascending. how can i sort in descending order. thanks

Could you post more sample code? Perhaps post the compare: method. — jakenberg
– jakenberg, Commented Jan 26, 2013 at 20:53
i don't have compare method, its very strange that it sort in ascending order, what i read that ascending is the default order in sortUsingSelector. do you have an example of method that can arrange the date in descending order? thank you — baste
– baste, Commented Jan 26, 2013 at 20:57
Look at @AKV answer. The NSSortDescriptor is what you're looking for. Just set ascending to NO like he did in the answer. — jakenberg
– jakenberg, Commented Jan 26, 2013 at 20:58

Anoop Vaidya · Accepted Answer · 2013-05-21 13:53:48Z

38

Sort the array by puting NO is ascending parameter:

NSSortDescriptor *descriptor=[[NSSortDescriptor alloc] initWithKey:@"self" ascending:NO];
NSArray *descriptors=[NSArray arrayWithObject: descriptor];
NSArray *reverseOrder=[dateArray sortedArrayUsingDescriptors:descriptors];

edited May 21, 2013 at 13:53

answered Jan 26, 2013 at 20:53

Anoop Vaidya

46.6k15 gold badges115 silver badges144 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

baste Over a year ago

where will i place this? sorry @AKV i'm new to ios

Anoop Vaidya Over a year ago

The place where you want to sort the array. After sorting the array use this array as datasource of your uitableView.

baste Over a year ago

you mean the reverseOrder will be my new content?

Julian · Accepted Answer · 2014-09-08 14:59:22Z

20

You can use a comparator block

NSArray *sortedArray = [array sortedArrayUsingComparator: ^(NSDate *d1, NSDate *d2) {
    return [d1 compare:d2];
}];

to reverse the order, just swap the dates

NSArray *sortedArray = [array sortedArrayUsingComparator: ^(NSDate *d1, NSDate *d2) {
    return [d2 compare:d1];
}];

or — as compare: returns a NSComparisonResult, which is actually typedef'ed to integer _{see below} — just multiply by -1

NSArray *sortedArray = [array sortedArrayUsingComparator: ^(NSDate *d1, NSDate *d2) {
    return -1* [d1 compare:d2];
}];

enum {
   NSOrderedAscending = -1,
   NSOrderedSame,
   NSOrderedDescending
};
typedef NSInteger NSComparisonResult;

edited Sep 8, 2014 at 14:59

Julian

9,3475 gold badges50 silver badges65 bronze badges

answered Jan 26, 2013 at 21:10

vikingosegundo

52.3k14 gold badges140 silver badges184 bronze badges

5 Comments

Carl Veazey Over a year ago

I'd suggest that, for readability's sake, the block be more explicit. Perhaps check if it's NSOrderedAscending and set to NSOrderedDescending explicitly, and vice versa. Both of the approaches (switching the argument order and multiplying by -1) strike me as depending too much on implementation details and not being clear to future readers.

baste Over a year ago

i try to understand your solution but i am new in ios and i cannot follow. sorry where will i place this? i load my array from dictionary in viewDidload

vikingosegundo Over a year ago

Wehre u u need it. U can just write it to a instanc variable. If u need more help show us all relevant code

Ganesh G Over a year ago

@ikinci viking, In my Array have 50 date objects, in this case how can i compare and sort it?

vikingosegundo Over a year ago

@G.Ganesh: just like you would with 2,5 or 5000

sarbuLopex · Accepted Answer · 2015-03-06 12:13:49Z

2

I'd use the built-in reverseObjectEnumerator method of NSArray

startimeArray = [startimeArray sortUsingSelector:@selector(compare:)];
startimeArray = [[startimeArray reverseObjectEnumerator] allObjects];

It's useful when you need the array sorted in ascending and descending order, so you can easily go back to the previous sort.

edited Mar 6, 2015 at 12:13

answered Jan 19, 2015 at 11:36

sarbuLopex

1,9461 gold badge18 silver badges24 bronze badges

Comments

Kevin ABRIOUX · Accepted Answer · 2016-02-08 16:01:27Z

1

There is the swift solution for the checked solution :

let sortedArray = randomArray.sortedArrayUsingComparator { (d1, d2) -> NSComparisonResult in
    return (d1 as! NSDate).compare(d2 as! NSDate)
}

answered Feb 8, 2016 at 16:01

Kevin ABRIOUX

17.9k12 gold badges98 silver badges106 bronze badges

Comments

Community · Accepted Answer · 2017-05-23 12:02:53Z

1

Swift 3.0

For anyone using swift 3.0 this DateHelper will save u some headache.

   filteredLogs.sort(by: {
        let firstElement = $0.timeStamp! as Date
        let secondElement = $1.timeStamp! as Date
        return firstElement.compare(.isEarlier(than: secondElement))
    })

The above code is a snippet from one of my projects. It uses the helper class to sort my logs with most recent dates at the left of the array. The $ sign is a positional parameter

edited May 23, 2017 at 12:02

CommunityBot

11 silver badge

answered May 17, 2017 at 14:29

Daniel

2,37823 silver badges20 bronze badges

Comments

jacai · Accepted Answer · 2016-07-13 22:32:52Z

In the Class where the Array elements are being initialized.

-(NSComparisonResult) compareArray: (id) element {
    Return [ArrayElement compare: [element ArrayElement]];
}



-(NSComparisonResult) compareArrayReverse: (id) element {
    Return [[element ArrayElement] compare: ArrayElement];
}

Then in the Class where your startimeArray is initialized:

@synthesize ArrayName;


-(void) sort: (BOOL) sel {
    if (sel) {
        [ArrayName sortUsingSelector: @selector(compareArray:)];
    } else {
        [ArrayName sortUsingSelector: @selector(compareArrayReverse:)];
    }    
}

Then in the main():

// Sort the array. sort = TRUE - ascending order, sort = FALSE - descending order.

[startimeArray sort: FALSE];

Collectives™ on Stack Overflow

How to sort an array of dates in descending order

6 Answers 6

3 Comments

5 Comments

Comments

Comments

Comments

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

3 Comments

5 Comments

Comments

Comments

Comments

Comments

Linked

Related