Update: Currently looking into NSSET's minusSet
links: http://stackoverflow.com/questions/1475636/comparing-two-arrays
Hi guys,
Could benefit from your wisdom here..
I'm using Coredata in my app, on first launch I download a data file and insert over 500 objects (each with 60 attributes) - fast, no problem.
Each subsequent launch I download an updated version of the file, from which I need to update all existing objects' attributes (except maybe 5 attributes) and create new ones for items which have been added to the downloaded file.
So, first launch I get 500 objects.. say a week later my file now contains 507 items..
I create two arrays, one for existing and one for downloaded.
NSArray *peopleArrayDownloaded = [CoreDataHelper getObjectsFromContext:@"person" :@"person_id" :YES :managedObjectContextPeopleTemp];
NSArray *peopleArrayExisting = [CoreDataHelper getObjectsFromContext:@"person" :@"person_id" :YES :managedObjectContextPeople];
If the count of each array is equal then I just do this:
NSUInteger index = 0;
if ([peopleArrayExisting count] == [peopleArrayDownloaded count]) {
NSLog(@"Number of people downloaded is same as the number of people existing");
for (person *existingPerson in peopleArrayExisting) {
person *tempPerson = [peopleArrayDownloaded objectAtIndex:index];
// NSLog(@"Updating id: %@ with id: %@",existingPerson.person_id,tempPerson.person_id);
// I have 60 attributes which I to update on each object, is there a quicker way other than overwriting existing?
index++;
}
} else {
NSLog(@"Number of people downloaded is different to number of players existing");
So now comes the slow part.
I end up using this (which is tooooo slow):
NSLog(@"Need people added to the league");
for (person *tempPerson in peopeArrayDownloaded) {
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"person_id = %@",tempPerson.person_id];
// NSLog(@"Searching for existing person, person_id: %@",existingPerson.person_id);
NSArray *filteredArray = [peopleArrayExisting filteredArrayUsingPredicate:predicate];
if ([filteredArray count] == 0) {
NSLog(@"Couldn't find an existing person in the downloaded file. Adding..");
person *newPerson = [NSEntityDescription insertNewObjectForEntityForName:@"person" inManagedObjectContext:managedObjectContextPeople];
Is there a way to generate a new array of index items referring to the additional items in my downloaded file?
Incidentally, on my tableViews I'm using NSFetchedResultsController so updating attributes will call [cell setNeedsDisplay];
.. about 60 times per cell, not a good thing and it can crash the app.
Thanks for reading :)
