transforming a plist in another nsdictionary - objective-c

Question

I'm not english, new to objective c and new to this website. But i hope you will understand my problem. I tried to use the search engine but i couldn't find a answer...
THE PROBLEM:
i have a plist file like this
<plist version="1.0">
<array>
<dict>
<key>ID</key>
<string>001</string>
<key>CAT</key>
<string>A</string>
<key>TITLE</key>
<string>AAAA01</string>
</dict>
<dict>
<key>ID</key>
<string>002</string>
<key>CAT</key>
<string>A</string>
<key>TITLE</key>
<string>AAAA02</string>
</dict>
<dict>
<key>ID</key>
<string>003</string>
<key>CAT</key>
<string>B</string>
<key>TITLE</key>
<string>BBBB01</string>
</dict>
.....
</array>
</plist>
so i have many entries like this. every entry has a category (CAT) like in my example "A" and "B".
now i need a code to transform this to the following:
NSArray
NSDictionary
CAT => "A"
VALUES => {"AAAA01","AAAA02"}
NSDictionary
CAT => "B"
VALUES => {"BBBB01", ...}
ETC.
MY SOLUTION:
i get the plist with the following code
NSString *path = [[NSBundle mainBundle] pathForResource:#"Dictonary" ofType:#"plist"];
arrayIndex = [[NSArray alloc] initWithContentsOfFile:path];
Now i have everything saved in the arrayIndex but then i dont find a way to transform the code in a new array to get my wanted result.
please can anybody help me?
THANK YOU very much!

Answer 1

This is straight programming.
It is more easily done in two steps saving trying to find an entry to add to.
// First create a dictionary of CAT and the values,
NSMutableDictionary *tempDict = [NSMutableDictionary dictionary];
for (NSDictionary *item in arrayIndex) {
NSString *cat = [item valueForKey:#"CAT"];
NSMutableArray *tempArray = [tempDict valueForKey:cat];
if (!tempArray) {
tempArray = [NSMutableArray array];
[tempDict setValue:tempArray forKey:cat];
}
NSString *v = [item valueForKey:#"TITLE"];
[tempArray addObject:v];
}
NSLog(#"tempDict: %#", tempDict);
// This may well be a good final result
// This step transforms the dictionary into a list of dictionaries
NSMutableArray *newList = [NSMutableArray array];
NSArray *keys = [[tempDict allKeys] sortedArrayUsingSelector:#selector(compare:)];
for (NSString *cat in keys) {
[newList addObject:[NSDictionary dictionaryWithObjectsAndKeys:
cat, #"CAT",
[tempDict valueForKey:cat], #"VALUES",
nil]];
}
NSLog(#"newList: %#", newList);