From iPhone Development Wiki

ASAssetQuery is used to list a set of assets on your iDevice. Assets are generally stored in /var/mobile/Library/Assets/

Here is how we list all the dictionary assets on the iDevice

ASAssetQuery * aq = [[%c(ASAssetQuery) alloc] initWithAssetType:@""];
NSError *err = nil;
[aq runQueryAndReturnError:&err];
HBLogDebug(@"err = %@", err);
NSArray *results = [aq results];
HBLogDebug(@"results = %@", results)

Note: for a dictionary you can also use DCSDictionaryAssetQuery

See also ASAsset.