sorting array of dictionaries

Question

HI i have a following array of dictionaries and and i want to sort the array using the the key "BirthDate" and my code is as follows

NSLog(@"nodeEventArray == %@", temp);
NSSortDescriptor *dateDescriptor = [NSSortDescriptor
                                    sortDescriptorWithKey:@"BirthDate"
                                    ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObject:dateDescriptor];
NSArray *sortedEventArray = [temp
                             sortedArrayUsingDescriptors:sortDescriptors];
NSLog(@"sortedEventArray == %@", sortedEventArray);

but I was unable to sort properly can any one please tell me how to sort the array of dictionary based on "BirthDate" key .Since birth date is coming as string from service

sample array of dictionaries:

   nodeEventArray = (
        {
        BirthDate = "05/04/1986";
        Email = "";
        FirstName = Test;
        IsSpouse = 0;
        LastName = Test;
        MiddleInitial = "";
        PatientID = "";
        Phone = "";
        ScacntronCSVId = 40409;
        SlotID = 1;
        UserName = "Tes_02192013010055";
    },
        {
        BirthDate = "02/14/1986";
        Email = "";
        FirstName = Guest;
        IsSpouse = 0;
        LastName = Guest;
        MiddleInitial = "";
        PatientID = "";
        Phone = "";
        ScacntronCSVId = 40410;
        SlotID = 2;
        UserName = "Gue_02192013014725";
    },
        {
        BirthDate = "02/17/1987";
        Email = "";
        FirstName = User;
        IsSpouse = 0;
        LastName = User;
        MiddleInitial = "";
        PatientID = "";
        Phone = "";
        ScacntronCSVId = 40411;
        SlotID = 3;
        UserName = "Use_02192013020726";
    }
    )

Perhaps this is what you are looking for: How to sort an NSMutableArray with custom objects in it? — cacba
– cacba, Commented Feb 19, 2013 at 7:50
When you say "sort properly" what do you mean? The "BirthDate" is only a string and so it will sort in ascending alphabetical order. — Fogmeister
– Fogmeister, Commented Feb 19, 2013 at 7:50

Fogmeister · Accepted Answer · 2013-02-19 08:05:09Z

1

I assume the array was coming from a server or something (hence the "Username" bit) but still, it would be better to store each user/event/whatever in an object with an NSDate. That way you can just sort by the date and it works.

However, if you want to sort this array then...

If you want to sort by BirthDate (using the date) then you'll need to convert the strings into actual NSDates.

NSDateFormatter *df = [[NSDateFormatter alloc] init];
df.dateFormat = @"MM/dd/yyyy";

[blah sortedArrayUsingComparator:^NSComparisonResult(NSDictionary *obj1, NSDictionary *obj2) {
    NSDate *date1 = [df dateFromString:[obj1 objectForKey:@"BirthDate"];
    NSDate *date2 = [df dateFromString:[obj2 objectForKey:@"BirthDate"];

    return [date1 compare:date2];
}];

This should do it.

It will convert the strings into dates and then compare them.

edited Feb 19, 2013 at 8:05

answered Feb 19, 2013 at 7:56

Fogmeister

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3 Comments

trojanfoe Over a year ago

He's using the stupid american format MM/dd/yy, not the excellent UK format dd/MM/yy :D

trojanfoe Over a year ago

Although I would encourage him to use NSDate to store the date anyway, rather than convert to it temporarily, for the obvious benefits that brings.

Fogmeister Over a year ago

True, I assumed the array was coming from a server or something (hence the "Username" bit) but still, it would be better to store each user in an object with an NSDate.

Sunil Pandey · Accepted Answer · 2013-02-19 12:55:39Z

0

Instead of using sortDescriptor you can use comparator

NSArray *sortedArray = [nodeEventArray sortedArrayUsingComparator: ^(id obj1, id obj2) {
        NSDateFormatter *dateFormator = [[NSDateFormatter alloc] init];
        NSDate *date1 = [dateFormator dateFromString:[[obj1 objectForKey:@"BirthDate"] stringByReplacingOccurrencesOfString:[[obj1 objectForKey:@"BirthDate"] lastPathComponent] withString:@"2013"]];
        NSDate *date2 = [dateFormator dateFromString:[[obj1 objectForKey:@"BirthDate"] stringByReplacingOccurrencesOfString:[[obj1 objectForKey:@"BirthDate"] lastPathComponent] withString:@"2013"]];
        if ([date1 earlierDate:date2] == date1) {
            return (NSComparisonResult)NSOrderedDescending;
        }else{
            return (NSComparisonResult)NSOrderedAscending;
        }

    }];

edited Feb 19, 2013 at 12:55

answered Feb 19, 2013 at 7:56

Sunil Pandey

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3 Comments

user564963 Over a year ago

working fine but need ascending and descending sorting as well but its working for ascending only not for descending and need to sort with month and date also not only with year.

Sunil Pandey Over a year ago

I have modified my logic according to your requirement. Also if you swap the NSOrderedAscending and NSOrderedDescending then your sorting will be reversed

user564963 Over a year ago

thanks for you update ,i got it and for ascending and descending i am using as mentioned below if (dobSorted == YES) { //For Ascending Order return [[df dateFromString:[dict1 objectForKey:@"BirthDate"]] compare:[df dateFromString:[dict2 objectForKey:@"BirthDate"]]]; }else{ //For Desending Order return -1 *[[df dateFromString:[dict1 objectForKey:@"BirthDate"]] compare:[df dateFromString:[dict2 objectForKey:@"BirthDate"]]]; }

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