ios - Predicates and combined filters in core data? -

i'm not using core data currently, i'm switch realm, if i'm sure thing work, vital way application works. have model 2 objects:

message: date - nsdate text - string images - one-to-many > image  image: imageurl - string message - many-to-one > image 

i have table view displays both images , messages. need know should go @ index path, when uitableview wants know. need able perform query akin to:

"give me ordered list of images , messages, messages sorted date , images sorted message.date".

how this?

as far know can't sort mixed array messages , images during coredata fetch request. here 1 possible way:

1. fetch messages , images separately
2. merge 2 arrays one
3. sort 1 array - (nsarray *)sortedarrayusingfunction:(nsinteger (*)(id, id, void *))comparator context:(void *)context

the function

 nsinteger sort(id item1, id item2, void *context) {         int v1 = [item1 iskindofclass[message class]]?item1.data:item1.message.date;         int v2 = [item2 iskindofclass[message class]]?item1.data:item1.message.date;         if (v1 < v2)             return nsorderedascending;         else if (v1 > v2)             return nsordereddescending;         else             return nsorderedsame;     }