objective c - NSSortDescriptor error : " [NSSortDescriptor count]: unrecognized selector sent to instance " -


i trying setup nsfetchedresultscontroller fetch request , keep getting error:

"[nssortdescriptor count]: unrecognized selector sent instance"

below code. model has 1 record trying fetch. following paul heagarty's 2010-2011 core data demo video set core data. 

nsfetchrequest *request = [nsfetchrequest fetchrequestwithentityname:@"temple"]; nssortdescriptor *sortdescriptor = [[nssortdescriptor alloc] initwithkey:@"name" ascending:no]; nsarray *sortdescriptors = [[nsarray alloc] initwithobjects:sortdescriptor, nil]; [request setsortdescriptors:sortdescriptors]; request.predicate = nil; self.fetchedresultscontroller = [[nsfetchedresultscontroller alloc] initwithfetchrequest:request managedobjectcontext:self.eventdatabase.managedobjectcontext sectionnamekeypath:nil cachename:nil]; 

// cause of error: assigning nssortdescriptor property expects nsarray fetchrequest.sortdescriptors = [nssortdescriptor sortdescriptorwithkey:@"name" ascending:yes];  // solution: wrap sort descriptor in array, fixes error fetchrequest.sortdescriptors = @[[nssortdescriptor sortdescriptorwithkey:@"name" ascending:yes]];

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