Sort NSDate objects in NSMutableArray using NSSortDescriptor?

Question

In my project, I'm getting some data from an APi and I retreive the data into a NSMutableArray by parsing the JSON. It has a key called "StartDate" which is of the format : " mm/dd/yyyy hh:mm:ss " as shown below

StartDate: "5/18/2013 12:00:00 AM"

I'm saving these data to a resultArray .There are also 4 more keys for an object as my JSON is of the form

{
    EventId: "xxxx",
    Title: "xxx",
    Location: "xxxx",
    StartDate: "5/18/2013 12:00:00 AM",
    Link: null
}

there are multiple such objects here. All that I need to do is to sort the contents of the resultArray based on date(either ascending or descending), I use the following code

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"StartDate" ascending:TRUE];
[resultArray sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];

But I;m getting a shuffled result, the sorting is not correct throughout, can anyone tel me where I had gone wrong .

Thanks

Maybe (probably) a dupe, but certainly not too localized. I can only suspect that the down-voters were too lazy to look up the dupes. — Hot Licks
– Hot Licks, Commented Jan 15, 2013 at 12:33
@HotLicks you are right! Thanks for your comment dude, i just posted so to let them be aware not to misuse their rights here! some of them see it as a hobby to downvote and flag! — DD_
– DD_, Commented Jan 15, 2013 at 13:02

AntonPalich · Accepted Answer · 2013-01-14 13:20:56Z

6

Should work

[resultArray sortUsingComparator:^NSComparisonResult(id a, id b) {

    static NSDateFormatter *dateFormatter = nil;

    if (!dateFormatter) {
        dateFormatter = [[NSDateFormatter alloc] init];
        dateFormatter.dateFormat = @"mm/dd/yyyy hh:mm:ss"; 
    }

    NSString *date1String = [a valueForKey:@"StartDate"];
    NSString *date2String = [b valueForKey:@"StartDate"];

    NSDate *date1 = [dateFormatter dateFromString:date1String];
    NSDate *date2 = [dateFormatter dateFromString:date2String];

    return [date1 compare:date2];
}];

answered Jan 14, 2013 at 13:20

AntonPalich

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2 Comments

DD_ Over a year ago

great answer man, i solved it using your answer, jsut changed dateformat from mm...to MM

Hot Licks Over a year ago

Another option would be to rearrange the strings into yyyymmdd order. Could be done with a few simple string ops.

Ankit Srivastava · Accepted Answer · 2013-01-14 12:01:00Z

3

Your StartDate seems to be in the string format and I believe its shuffling it for string.. You should convert to NSDate first and than apply this descriptor... Hoping this helps.

answered Jan 14, 2013 at 12:01

Ankit Srivastava

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3 Comments

DD_ Over a year ago

Thanks for your help, but I don't have the permission to change the APi format, so should i replace each date key of my array after converting to the date format?

Ankit Srivastava Over a year ago

You must be storing it in the a data model I guess, where you can specify the property of this model object as NSDate and while feeding it to the object convert it to date... or simpler you can do what you are saying but that is not the standar way to do that... but what the heck... you should try your approach first and if it works later you can convert it to data model objects

DD_ Over a year ago

this makes sense, but you could see more simple way by checking the accepted answer.Thanks

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