Cocoa Core Data efficient way to count entities

Question

I read much about Core Data.. but what is an efficient way to make a count over an Entity-Type (like SQL can do with SELECT count(1) ...). Now I just solved this task with s

Answer 1

To be clear, you aren't counting entities, but instances of a particular entity. (To literally count the entities, ask the managed object model for the count of its entities.)

To count all the instances of a given entity without fetching all the data, the use -countForFetchRequest:.

For example:

NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity: [NSEntityDescription entityForName: entityName inManagedObjectContext: context]];

NSError *error = nil;
NSUInteger count = [context countForFetchRequest: request error: &error];

[request release];

return count;