how to edit coredata value then save context to overwrite old values?

Question

I am trying to edit a item in one of my coredata tables/entities. I am not 100% sure how to do this but I think its along these lines.

First you create the context, then fetchrequest the entity using a predicate to select the exact item from the table/entity. then save these values into the correct var type update the values then some how overwrite the existing item with the new values.

The last part is where I am stuck, this is the code I currently have:

- (void)editSelectedInstall:(NSString *)invGuid {
    NSManagedObjectContext *context = [self managedObjectContext];


    if (context == nil) {
        NSLog(@"Nil");
    }
    else {


        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
        NSEntityDescription *entity = [NSEntityDescription entityForName:@"Install" inManagedObjectContext:context];
        [fetchRequest setEntity:entity];

        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"invGUID==%@",invGuid];
        [fetchRequest setPredicate:predicate];

        NSError *error = nil;
        NSArray *myArray = [context executeFetchRequest:fetchRequest error:&error];
        NSMutableDictionary *myDictionary = [myArray objectAtIndex:0];
        NSLog(@"%@", myDictionary);




// Here I will update the values & then save the context? 
// For example I think I am to update the items like this:

myDictionary.num = @"1234";
myDictionary.name = @"new name";
    }


}

I think I'm almost there I just need help saving the context so that it overwrites the previous values.

Answer 1

Try this:

//loop through result set and update as required
for (Install *temp in myArray) {
    temp.num = @"1234";
    temp.name = @"New name";
}

//save
[context save:&error];