Sorting the Dates in Array

Question

I have an array as follow which comes from Sqlite DB & are in string:

(

{ 
 id=1;
duedate = "01-Apr-2013";
},

{
 id=2;
duedate = "01-May-2013";
},

{
id=3;
duedate = "01-Jun-2013";
},

{
 id=4;
duedate = "11-Jul-2013";
}

)

My code for sorting the array

NSSortDescriptor *sortDesc = [[NSSortDescriptor alloc] initWithKey:@"duedate" ascending:YES];
[assessment_list sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];

But This give wrong sorted array as follow

(

{ 
 id=1;
duedate = "01-Apr-2013";
},

{
id=3;
duedate = "01-Jun-2013";
},

{
id=2;
duedate = "01-May-2013";
},

{
 id=4;
duedate = "11-Jul-2013";
}

)

I searched but i didn't found this issue

DivineDesert · Accepted Answer · 2013-03-25 09:31:42Z

2

This is because it is sorted alphabetically.

For sorting on dates, you need to implement a method something like this

NSInteger dateSort(id dict1, id dict2, void* context){
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"mm/dd/yyyy"];
NSDate *date1 = [formatter dateFromString:[dict1 objectForKey:@"duedate"]];
NSDate *date2 = [formatter dateFromString:[dict2 objectForKey:@"duedate"]];
    return [[date1 compare:date2];
}

and call the function like this

[dateArray sortUsingFunction:dateSort context:NULL];

edited Mar 25, 2013 at 9:31

answered Mar 25, 2013 at 9:26

DivineDesert

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2 Comments

user1673099 Over a year ago

what should be written in place of string1 & string2? My array count is 4.

DivineDesert Over a year ago

return [date2 compare:date1] to get it in descending order

Anoop Vaidya · Accepted Answer · 2013-03-25 09:31:50Z

2

You need to do it in parts.

Part 1 : Convert these strings into NSDate.

NSDateFormatter *df=[NSDateFormatter new];
[df setDateFormat:@"dd-MMM-yyyy"];
NSDate *date=[df dateFromString:string];

Part 2 : Then use sorting technique/ way (selector, descriptor etc).

edited Mar 25, 2013 at 9:31

answered Mar 25, 2013 at 9:26

Anoop Vaidya

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Comments

Anupdas · Accepted Answer · 2013-03-25 09:41:12Z

You need to convert the strings to date to sort them

   NSArray *datesStringArray = @[@{@"duedate": @"01-Jun-2013"},@{@"duedate": @"01-Dec-2013"},@{@"duedate": @"01-Apr-2013"},@{@"duedate": @"11-Jul-2013"},];

    NSDateFormatter *dateFormatter = [NSDateFormatter new];
    [dateFormatter setDateFormat:@"dd-MMM-yyyy"];

    NSArray *sortedDateStringArray = [datesStringArray sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {

        NSDictionary *dict1 = (NSDictionary *)obj1;
        NSString *string1 = dict1[@"duedate"];
        NSDictionary *dict2 = (NSDictionary *)obj2;
        NSString *string2 = dict2[@"duedate"];

        NSDate *date1 = [dateFormatter dateFromString:string1];
        NSDate *date2 = [dateFormatter dateFromString:string2];

        return [date1 compare:date2];

    }];

Arthur · Accepted Answer · 2013-03-25 09:27:52Z

0

You can convert your dates into time interval.

int t = [[NSDate date] timeIntervalSince1970];

and sort your array like array with int values

answered Mar 25, 2013 at 9:27

Arthur

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