Question

my array jokesarray has elements like the following. I am trying to sort by nested element “sec”.

Everytime I run this I get a different sort order or every time I come back to the same view (my sorting code is in viewwillappear). Why?

    {
       "4eb57e72c7e24c014f000000" : {
         "_id" : {
           "$id" : "4eb57e72c7e24c014f000000"
         },
         "author" : "tim",
         "comments" : [],
         "created": {
           "sec" : 1320517234,
           "used" : 856000
         },
         "picture" : "http://someurl.com",
         "text" : "this is a test",
         "title" : "test",
         "type" : ["test"]
       }

    jokesArray = [unSortedContentArray sortedArrayUsingFunction:Sort_Created_Comparer context:self]; 

    NSInteger Sort_Created_Comparer(id array1, id array2, void *context)
{

    int v1 = (int)[[array1 objectForKey:@"created"] objectForKey:@"sec"];
    int v2 = (int)[[array2 objectForKey:@"created"] objectForKey:@"sec"];
    if (v1 < v2)
        return NSOrderedAscending;
    else if (v1 > v2)
        return NSOrderedDescending;
    else
        return NSOrderedSame;
}

Answer 1

[[array1 objectForKey:@"created"] objectForKey:@"sec"]

returns a pointer to an object; in your case, an NSNumber object. When you cast it to int like:

(int)[[array1 objectForKey:@"created"] objectForKey:@"sec"]

you’re casting the memory address where that object is located to an int value, since -objectForKey: returns a pointer to an object.

As you’re not interested in the memory address but the underlying int value instead, use -[NSNumber intValue]:

int v1 = [[[array1 objectForKey:@"created"] objectForKey:@"sec"] intValue];

Also, it’s odd that you’ve named your dictionaries array1 and array2 — they aren’t arrays.

---

Edit: Alternatively, you could let NSNumber do the comparison for you:

NSInteger Sort_Created_Comparer(NSDictionary *d1, NSDictionary *d2, void *context)
{
    NSNumber *n1 = [[d1 objectForKey:@"created"] objectForKey:@"sec"];
    NSNumber *n2 = [[d2 objectForKey:@"created"] objectForKey:@"sec"];
    return [n1 compare:n2];
}