CODEWITHSUNDEEP
iosiphonexcodecore-datansmanagedobjectcontext
Pheepster
Pheepster

Reputation: 6357

Core Data: get lowest value of an attribute

Still somewhat new to Core Data and am stuck on a problem. I have an int property in a managed object called index. I need to loop through all managed objects and determine the highest index value. I chose descending in my sort descriptor so that I can access the array object at index 0. I know this should be simple, but here is my current code:

+(NSInteger)getHighIndexNumber{
    NSManagedObjectContext *context = [[FavesDataModel sharedDataModel] mainContext];
    NSFetchRequest *fetchReq = [[NSFetchRequest alloc] init];

    NSSortDescriptor *sortByIndex = [[NSSortDescriptor alloc] initWithKey:@"index" ascending:NO];
    [fetchReq setSortDescriptors:[NSArray arrayWithObject:sortByIndex]];

    NSEntityDescription *entity = [NSEntityDescription entityForName:[Favorite entityName] inManagedObjectContext:context];
    [fetchReq setEntity:entity];

    return ???
}

Any suggestions? Thanks!

Upvotes: 1

Views: 162

Answers (1)

Martin R
Martin R

Reputation: 539745

Your code looks OK, so just execute the fetch request:

NSError *error;
NSArray *objects = [context executeFetchRequest:fetchReq error:&error];
if (objects == nil) {
    // An error occurred, report error and return nil?
    NSLog(...);
    return nil;
} else if ([objects count] == 0) {
    // No object found, return nil?
    return nil;
} else {
    // At least one object found, return the first one:
    return objects[0];
}

Note that since you need only the first element, you can improve the performance by setting

[fetchReq setFetchLimit:1]

Upvotes: 3

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