NSSortDescriptor should sort NSDates
It appears NSSortDescriptor should be a fairly easy class to work with.
I have stored in CoreData an entity with an attribute of type NSDate appropriately named @"date". I am attempting to apply a sort descriptor to a NSFetchRequest and it doesn't appear to be returning the results I had hoped for.
The result I am hoping for is to simply arrange the dates in chronological order, and instead they are returned in the order for which they were added to CoreData.
Perhaps you can offer guidance?
Is the parameter 'ascending' what controls the sort?
Some Code:
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entityDesc = [NSEntityDescription entityForName:@"Data" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entityDesc];
[fetchRequest setFetchBatchSize:10];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
Separate sort routines (functions or blocks) look like overkill to me. I am routinely sorting Core Data entities by date attribtues just with the sort descriptor method you show in your code. It works perfectly every time.
Clearly, there must be some other mistake.
Data.h , in your case). NSDate . Here is more information on NSSortDescriptors
Or if you want to sort an array of dates after getting them for coreDate:
//This is how I sort an array of dates.
NSArray *sortedDateArray = [dateArray sortedArrayUsingFunction:dateSort context:NULL];
// This is a sorting function
int dateSort(id date1, id date2, void *context)
{
return [date1 compare:date2];
}
Here is code straight from apple for sorting integers (just modify to sort dates):NSComparator
NSArray *sortedArray = [array sortedArrayUsingComparator: ^(id obj1, id obj2) {
if ([obj1 integerValue] > [obj2 integerValue]) {
return (NSComparisonResult)NSOrderedDescending;
}
if ([obj1 integerValue] < [obj2 integerValue]) {
return (NSComparisonResult)NSOrderedAscending;
}
return (NSComparisonResult)NSOrderedSame;
}];
Add timestamp - String type field in CoreData entity
creationDate
during insertion of the record
NSManagedObject *newCredetial = [NSEntityDescription insertNewObjectForEntityForName:@"Name" inManagedObjectContext:context];[newCredetial setValue:[self getDate] forKey:@"creationDate"];
date function
- (NSString *)getDate{
NSDate *date = [NSDate date];
NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
formatter.dateFormat = @"ddMMyyyyhhmmssss";
return [formatter stringFromDate:date];}
and Use Short Description during Fetching module
NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
NSFetchRequest *fetchRequest1 = [[NSFetchRequest alloc] initWithEntityName:@"Name"];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"creationDate" ascending:NO];
[fetchRequest1 setSortDescriptors:@[sortDescriptor]];
arrNameInfo = [[managedObjectContext executeFetchRequest:fetchRequest1 error:nil] mutableCopy];