objective c - How to use predicate on arrayController and Core Data -



objective c - How to use predicate on arrayController and Core Data -

i have nsoutlineview shows info core info store. info presented using nsarraycontroller linked managedobjectcontext , displayed in nsoutlineview using nstreecontroller (much described here). filter info shown using nspredicate (or else) can't work. note osx , not ios can't utilize nsfetchedresultscontroller.

i able retrieve right info , store these in nsarray. however, enabling automatic update of see in outlineview using filtered info not work. have:

[arraycontroller setmanagedobjectcontext:_coredatahelper.context]; nsfetchrequest *request = [[nsfetchrequest alloc] init]; nsentitydescription *entity = [nsentitydescription entityforname:@"sdrdfileobject" inmanagedobjectcontext:_coredatahelper.context]; [request setentity:entity]; nsnumber *directionlimit = @1; nspredicate *predicate = [nspredicate predicatewithformat:@"direction = %@", directionlimit]; [request setpredicate:predicate]; nserror *error; [arraycontroller setcontent:[_coredatahelper.context executefetchrequest:request error:&error]]; [_coredatahelper.context reset]; [arraycontroller fetch:self]; [outlineview reloaddata];

as can see question close one, still struggling. if work using setcontent arraycontroller assume run problem having mismatch between core info context , content of arraycontroller. suggestions or illustration how correctly appreciated.

suggestion 1: seek ditching array controller.

i'm not exclusively sure objective of author of first link direct is, he/she that, @ to the lowest degree in mutual nsoutlineview setup, little odd. controller object required extract values core info , display them in outline view nstreecontroller. tutorial on other hand suggests interposing array controller: "in nib file you’ll need array controller bound nsmanagedobjectcontext, set entity mode, , fetch predicate of parent == nil. fetch our top level objects – entities without parent." sentiment should doing tree controller not array controller. lean in mind think first thing should you're info appearing correctly tree controller, 1 time you've achieved this, can start think filtering outline view.

suggestion 2: filtering

unlike nsarraycontroller, nstreecontroller objects have no filterpredicate in class reference. i'm not sure why is, outline view have implement filtering behaviour yourself. can bit tricky, it's not difficult. instance, in 1 of projects, have big drag-and-drop compatible tree controller/outline view setup apes way xcode filters files when type search bar positioned in bottom left-hand corner. did adding category nstreecontroller called -filtercontentusingpredicate returns array. 1 time filtering complete, utilize phone call [-nstreecontroller setcontent:] update contents of outline view reflect filter.

objective-c cocoa core-data nspredicate nsarraycontroller

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