sort a dictionary by a key from an inner dictionary - objective-c

Question

i have a dictionary which i want to sort it according to a key from an inner dictionary. Each key in the super dictionary has a dictionary as value. As an example to illustrate what i'm talking about, here is a super dictionary with inner dictionaries respectively to each key.
{
key1 = {count = 2},
key2 = {count = 1}
}
thus the count key has to be the key used for the sorting. For now i know only how to sort arrays and i didn't encounter sorting dictionaries before. Any help will be appreciated.

Answer 1

get the array out of dictionary & sort it
NSArray* values = [myDict allValues];
NSArray* sortedValues = [values sortedArrayUsingSelector:#selector(comparator)];
another way to do it to make NSSortDescriptor
keyDescriptor = [[[NSSortDescriptor alloc] initWithKey:#"count" ascending:YES] autorelease];
sortDescriptors = [NSArray arrayWithObject:keyDescriptor];
sortedArray = [myArray sortedArrayUsingDescriptors:sortDescriptors];
I pulled the code from Sort Descriptor Programming Topics. Also, Key-Value Coding comes into play, in that sortedArrayUsingDescriptors: will send a valueForKey: to each element in myArray, and then use standard comparators to sort the returned values.

Answer 2

Here's one way:
NSDictionary * dict1 = [[NSDictionary alloc]initWithObjectsAndKeys:[NSNumber numberWithInt:2], #"count", nil];
NSDictionary * dict2 = [[NSDictionary alloc]initWithObjectsAndKeys:[NSNumber numberWithInt:3], #"count", nil];
NSArray * arrayOfDictionaries = [[NSArray alloc]initWithObjects:dict1, dict2, nil];
NSArray * sortedArray = [arrayOfDictionaries sortedArrayUsingComparator:^NSComparisonResult(NSDictionary * obj1, NSDictionary * obj2) {
// are points equal?
if ([obj1[#"count"] intValue] != [obj2[#"count"] intValue]) {
// points not equal, compare points
if ([obj1[#"count"] intValue] > [obj2[#"count"] intValue])
return (NSComparisonResult)NSOrderedAscending;
else
return (NSComparisonResult)NSOrderedDescending;
}
else {
return (NSComparisonResult)NSOrderedSame;
}
}];
Let me know how it goes!

Answer 3

Okay, just to add to what others had posted (Thank you!) i also found my own solution which goes like this:
NSArray *keysByFrequency = [object keysSortedByValueUsingComparator:^NSComparisonResult(NSDictionary* obj1, NSDictionary* obj2) {
return [obj1[#"count"] compare:obj2[#"count"]];
}];
NSMutableArray *tags = [[NSMutableArray alloc] init];
for (int i = keysByFrequency.count-1; i >= 0; i--) {
[tags addObject:#{#"tag" : keysByFrequency[i], #"count" : object[keysByFrequency[i]][#"count"], #"type" : object[keysByFrequency[i]][#"type"]}];
}