订购返回的NSArray CoreData实体

Question

I am trying to arrange the returned core data entities by the value of a attribute "depart time" currently I have this code, but the order is not changed they are saved to the array in the same order regardless of NSSortDescriptor

NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"Device"];

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"thetrip=%@",searchid];

[request setEntity:[NSEntityDescription entityForName:@"Device" inManagedObjectContext:managedObjectContext]];

[request setPredicate:predicate];
self.device = [[managedObjectContext executeFetchRequest:request error:nil] mutableCopy];
[NSSortDescriptor sortDescriptorWithKey:@"departtime" ascending:YES];
NSLog(@"the predicate is= %@", predicate);

NSError *error = nil;

NSArray *results = [managedObjectContext executeFetchRequest:request error:&error];

NSArray *areuslter=[self.device valueForKey:@"arriveairport"];
NSArray *areusltses=[self.device valueForKey:@"thetrip"];

Answer 1

You are not actually doing anything with the SortDescriptor there. In fact you are ignoring it completely.

Try this instead...

NSSortDescriptor *timeSD = [NSSortDescriptor sortDescriptorWithKey:@"departtime" ascending:YES];
[request setSortDescriptors:@[timeSD]];

That will add the sort descriptor to the request.