Sorting an NSArray by an NSDictionary value - objective-c

Question

I'm trying to sort an array that would look something like this:
(please ignore the fact these people are well past any living age! I just needed large numbers)
NSDictionary *person1 = [NSDictionary dictionaryWithObjectsAndKeys:#"sam",#"name",#"28.00",#"age",nil];
NSDictionary *person2 = [NSDictionary dictionaryWithObjectsAndKeys:#"cody",#"name",#"100.00",#"age",nil];
NSDictionary *person3 = [NSDictionary dictionaryWithObjectsAndKeys:#"marvin",#"name",#"299.00",#"age",nil];
NSDictionary *person4 = [NSDictionary dictionaryWithObjectsAndKeys:#"billy",#"name",#"0.0",#"age",nil];
NSDictionary *person5 = [NSDictionary dictionaryWithObjectsAndKeys:#"tammy",#"name",#"54.00",#"age",nil];
NSMutableArray *arr = [[NSMutableArray alloc] initWithObjects:person1,person2,person3,person4,person5,nil];
// before sort
NSLog(#"%#",arr);
NSSortDescriptor *ageSorter = [[NSSortDescriptor alloc] initWithKey:#"age" ascending:YES];
[arr sortUsingDescriptors:[NSArray arrayWithObject:ageSorter]];
// after sort
NSLog(#"%#",arr);
Now before sort the output would be:
2010-07-21 10:46:31.898 Sorting[70673:207] (
{
age = "28.00";
name = sam;
},
{
age = "100.00";
name = cody;
},
{
age = "299.00";
name = marvin;
},
{
age = "0.0";
name = billy;
},
{
age = "54.00";
name = tammy;
}
)
and after the sort:
2010-07-21 10:46:31.900 Sorting[70673:207] (
{
age = "0.0";
name = billy;
},
{
age = "100.00";
name = cody;
},
{
age = "28.00";
name = sam;
},
{
age = "299.00";
name = marvin;
},
{
age = "54.00";
name = tammy;
}
)
As you can see it does sort it, but from my understanding it's sorting by string. I've tried but after a few days of failure of trying to write a method that would sort this for me im still at a loss. What would be the best approach and accomplishing this so it sorts by a numeric value?

Answer 1

Although I question the use of strings here, the simplest way to work with that data with be:
[array sortedArrayUsingComparator:^(NSDictionary *item1, NSDictionary *item2) {
NSString *age1 = [item1 objectForKey:#"age"];
NSString *age2 = [item2 objectForKey:#"age"];
return [age1 compare:age2 options:NSNumericSearch];
}];
Or, using Objective-C's more recent subscripting features:
[array sortedArrayUsingComparator:^(NSDictionary *item1, NSDictionary *item2) {
return [item1[#"age"] compare:item2[#"age"] options:NSNumericSearch];
}];

Answer 2

Easiest would be storing the age as a number instead of a string.