ios - CoreData Sort by relation -

my relation shown on picture below.

i'd sort events first in active promotion , start date. promotion active if current date between start , end date. unfortunately, because of coredata, i'm not able use transient properties sorting. in controller i'm not using fetch controller.

is there way achieve that?

update:

i've following sort descriptors:

// first incorrect [nssortdescriptor(key: "promotion.start", ascending: false),  nssortdescriptor(key: "start", ascending: true)] 

predicates (they're ok, though):

let promotionspredicate =     nspredicate(format: "(%@ >= promotion.start && %@ <= promotion.end) && " +                 "(any promotion.cities.id == %@)", nsdate(), nsdate(), objectid) let eventspredicate =     nspredicate(format: "start >= %@ && venue.city.id == %@",                                 nsdate(), objectid)  let subpredicates = [eventspredicate, promotionspredicate]                     let compoundpredicate nscompoundpredicate(orpredicatewithsubpredicates: subpredicates) 

and request (i'm using corestore, idea should clear):

class func pagedeventsforpredicatesortedbyinpromoandstartdate(predicate: nspredicate,                                                               descriptors: [nssortdescriptor],                                                               fetchoffset: int,                                                               fetchlimit: int) -> [event] {      return corestore.fetchall(from(event),                               where(predicate),                               orderby(descriptors),                               tweak { (fetchrequest) -> void in                                 fetchrequest.fetchoffset = fetchoffset                                 fetchrequest.fetchlimit = fetchlimit                                 fetchrequest.returnsobjectsasfaults = false         }) ?? [] } 

as understood have event objects, in proper order. such complicated order, includes relationship, far know have fetch events , sort them using nsarray's method

- (nsarray<objecttype> *)sortedarrayusingcomparator:(nscomparator)cmptr 

here pieces of code

1. fetch core data

// right context here nsmanagedobjectcontext *yourcontext;  nsfetchrequest *request = [nsfetchrequest fetchrequestwithentityname:@"event"]; // line, predicate nil default, other required predicate written here request.predicate = nil;  __block nsarray *results = nil; [yourcontext performblockandwait:^{     nserror *error = nil;    results = [yourcontext executefetchrequest:request error:&error];         if (error) {             // handle error here         }     }];

fetch made manually core methods , may use magical record or other framework works core data make in row.

2. sort results

__weak typeof(self) weakself = self;  nsdate *now = [nsdate date]; nsarray *sortedresults = [results sortedarrayusingcomparator:^nscomparisonresult(event *_nonnull obj1, event *_nonnull obj2) {      bool isobj1inactivepromotion = [weakself date:now isbetweendate:obj1.promotion.start anddate:obj1.promotion.end];     bool isobj2inactivepromotion = [weakself date:now isbetweendate:obj2.promotion.start anddate:obj2.promotion.end];      // if eather in active promotion or no, compare them start date of event     if (isobj1inactivepromotion == isobj2inactivepromotion) {         return [obj1.start compare:obj2.start];     } else {         return isobj1inactivepromotion ? nsorderedascending : nsordereddescending;     } }]; 

3. additional method work nsdate

this method used in sorting method

+ (bool)date:(nsdate *)date isbetweendate:(nsdate *)begindate anddate:(nsdate *)enddate {     if ([date compare:begindate] == nsorderedascending) {         return no;     }      if ([date compare:enddate] == nsordereddescending) {         return no;     }      return yes; } 

i could't check code obvious reasons, sorry typos if are.