using NSPredicate on nested dictionary/array - objective-c

Question

I'm trying to use a deeply nested data structure and NSPredicate to filter that data.
I have a plist file like this:
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>images-ipad</key>
<array>
<dict>
<key>categories</key>
<array>
<string>standard</string>
</array>
<key>name</key>
<string>Default</string>
<key>plist</key>
<string>cardSheet.plist</string>
<key>png</key>
<string>cardSheet.png</string>
</dict>
<dict>
<key>categories</key>
<array>
<string>standard</string>
</array>
<key>name</key>
<string>Optional</string>
<key>plist</key>
<string>cardSheet.plist</string>
<key>png</key>
<string>cardSheet.png</string>
</dict>
<dict>
<key>categories</key>
<array>
<string>christmas</string>
<string>holiday</string>
<string>standard</string>
</array>
<key>name</key>
<string>christmas</string>
<key>plist</key>
<string>cardSheet.plist</string>
<key>png</key>
<string>cardSheet.png</string>
</dict>
</array>
</dict>
</plist>
Which I load into an NSDictionary via dictionWithContentsOfFile.
I then want to get the elements of the array images-ipad that are in the category 'standard' via NSPredicate. I think this is possible, but I've not been able to accomplish it, and the docs don't seem to cover nested data structures.
So, I've tried this:
NSPredicate *getcat = [NSPredicate predicateWithFormat:#"ANY images-ipad.categories == 'holiday'"];
NSArray *res = [[dict objectForKey:#"images-ipad"] filteredArrayUsingPredicate:getcat];
but it does not return any elements, which brings me to stackoverflow. Thanks in advance.

Answer 1

Since you're filtering the result of [dict objectForKey:#"images-ipad"], you shouldn't include that string in the key path of the predicate, as it's basically equivalent to looking up images-ipad.images-ipad.categories, which doesn't exist.