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up vote 0 down vote favorite

Assuming I have an NSMutableArray which is loaded from file:

searchTermsArray = [[NSMutableArray alloc] initWithContentsOfFile: yourArrayFileName];

inside this array items are key objects

for (int i=0; i<[searchTermsArray count]; i++) {
            NSLog(@"for array item %d: %@ - %@",i,[[searchTermsArray objectAtIndex:i] objectForKey:@"title"], [[searchTermsArray objectAtIndex:i] objectForKey:@"theCount"] );
        }

(which means that each array element (item) has 2 keys values:

searchTermsArray[0] = title (string) , theCount (also a string, but made out of integers)

Question: how should I sort "searchTermsArray" array from higher to lower based on "theCount" value?

(I am looking at the following code but it is not fitting the structure/syntax)

NSSortDescriptor *Sorter = [[NSSortDescriptor alloc] initWithKey:@"title" ascending:NO];
        [searchTermsArray sortUsingDescriptors:[NSArray arrayWithObject:Sorter]];
        [Sorter release];
share|improve this question

3 Answers 3

up vote 3 down vote accepted

Shouldn't you be sorting based on theCount key?

NSSortDescriptor * descriptor = [NSSortDescriptor sortDescriptorWithKey:@"theCount" ascending:NO];
[searchTermsArray sortUsingDescriptors:[NSArray arrayWithObject:descriptor]];
share|improve this answer
    
yep, that works. –  user745098 Jun 20 '11 at 14:32
    
Deepak - Elegant clean and nice! thank you mate! –  chewy Jun 20 '11 at 14:39
up vote 2 down vote

I am not sure if there is a better way to do so. But this thing works.

NSInteger intSort(id param1, id param2, void *context) {

    NSDictionary *dict1 = (NSDictionary *)param1;
    NSDictionary *dict2 = (NSDictionary *)param2;

    NSInteger dict1KeyCount = [[dict1 objectForKey:@"count"] intValue];
    NSInteger dict2KeyCount = [[dict2 objectForKey:@"count"] intValue];

    if (dict1KeyCount < dict2KeyCount) {
        return NSOrderedAscending;
    }else if (dict1KeyCount > dict2KeyCount) {
        return NSOrderedDescending;
    }else {
        return NSOrderedSame;
    }
}


// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.

- (void)viewDidLoad {
    NSMutableArray *array = [[NSMutableArray alloc] initWithObjects:[NSDictionary dictionaryWithObjectsAndKeys:@"two", @"title", @"2", @"count", nil],
                             [NSDictionary dictionaryWithObjectsAndKeys:@"three", @"title", @"3", @"count", nil],
                                [NSDictionary dictionaryWithObjectsAndKeys:@"one", @"title", @"1", @"count", nil], nil];

    NSArray *sortedArray = [array sortedArrayUsingFunction:intSort context:NULL];

    for (NSDictionary *dict in sortedArray) {
        NSLog(@"%d", [[dict objectForKey:@"count"] intValue]);
    }

    [super viewDidLoad];
}
share|improve this answer
    
Ok, and if you want to sort in descending order, then just swap NSOrderedAscending and NSOrderedDescending in the intSort function. –  user745098 Jun 20 '11 at 14:29
    
thanks for the answer, can u be slightly clearer regarding the params and context ? –  chewy Jun 20 '11 at 14:34
    
It is basically the comparator function, which will define how your array will get sorted. We take parameters as id so that it supports all sort of objects. Since, your array contains Dictionary, we cast it to it and further tell the comparator function how the comparison has to be done. Also, please note that deepak's answer works too. It is short and nice. –  user745098 Jun 20 '11 at 14:37
    
Thanks pratikshabhisikar I appreciate the time and effort. –  chewy Jun 20 '11 at 14:45
up vote 0 down vote

The NSSortDescriptor is usually used to sort objects of a class. You pass the name of the property in that class to be compared with others. Since what you have in your array actually seems to be a NSDictionary, the NSSortDescriptor might not be the best way to approach this problem. Besides, your objects in the dictionary must have a type, so I would try to sort the array myself in one of the classic methods if I were you.

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