Get all results of a NSFetchRequest in an NSArray

Question

In my app I do this thing to abtain all specific value from an entity

NSManagedObjectContext *context = [[self sharedAppDelegate] managedObjectContext];
NSError *error = nil;
NSFetchRequest *req = [NSFetchRequest fetchRequestWithEntityName:@"Structure"];
[req setPropertiesToFetch:@[@"id_str"]];
[req setResultType:NSDictionaryResultType];

NSArray *id_str_BD = [context executeFetchRequest:req error:&error];

int this way I obtain a NSArray of NSDictionaryies but I want directly an array of values. What's a fast way to obtain it without loops?

An array of what values? The individual values of the `id_str` attribute? — Tom Harrington, May 16 '14 at 16:09
@TomHarrington I guess the OP would retrieve an array of `id_str` values..but maybe I'm wrong — Lorenzo B, May 16 '14 at 17:21

score 1 · Accepted Answer · answered May 16 '14 at 17:19

I agree with Tom. What values?

Anyway, you can accomplish it through KVC. For example,

NSFetchRequest* fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"Structure"];
[fetchRequest setPropertiesToFetch:@[@"id_str"]];

NSArray* results = [[self managedObjectContext] executeFetchRequest:fetchRequest error:nil];
NSArray* ids = [results valueForKey:@"id_str"];

NSLog(@"%@", ids);

NOTES

Do not pass nil for the error. ALWAYS check for a possible error (for the sake of simplicity I don't use it in this code snippet)
I would rename id_str to idStructure

Get all results of a NSFetchRequest in an NSArray

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