It’s been a pretty long process for me to get working with Core Data. It’s no PHP thats for sure. In any case, below is a bunch different tasks that I was required to figure out for my development. Hopefully it helps.
Loading a specific object based on its value
[code]
FLAppDelegate* appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext* context = [appDelegate managedObjectContext];
NSEntityDescription* enetityDescription = [NSEntityDescription entityForName:@"DataPointObject" inManagedObjectContext:context];
NSFetchRequest* request = [[NSFetchRequest alloc] init];
[request setEntity:enetityDescription];
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"(idValue = %@)", [NSNumber numberWithInteger:idValue]];
[request setPredicate:predicate];
NSArray* array = [context executeFetchRequest:request error:&error];
[/code]
Check if Object Exists
[code]
FLAppDelegate* appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext* context = [appDelegate managedObjectContext];
NSEntityDescription* enetityDescription = [NSEntityDescription entityForName:@"DataPointObject" inManagedObjectContext:context];
NSFetchRequest* request = [[NSFetchRequest alloc] init];
[request setEntity:enetityDescription];
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"(idValue = %@)", [NSNumber numberWithInteger:idValue]];
[request setPredicate:predicate];
NSError* error;
NSInteger count = [context countForFetchRequest:request error:&error];
if (count == NSNotFound || count == 0) {
return NO;
}
[/code]
limit fetching request (ie load 100 objects)
[code]
FLAppDelegate* appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext* context = [appDelegate managedObjectContext];
NSEntityDescription* enetityDescription = [NSEntityDescription entityForName:@"DataPointObject" inManagedObjectContext:context];
NSFetchRequest* request = [[NSFetchRequest alloc] init];
[request setEntity:enetityDescription];
NSSortDescriptor* sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"idValue" ascending:NO];
[request setSortDescriptors:@[sortDescriptor]];
[request setFetchLimit:100];
NSError* error;
NSArray* array = [context executeFetchRequest:request error:&error];
[/code]