Updating an array of custom class objects from second array

Question

I have an array (items) of custom class objects (catalogItem) each catalogItem has various properties one of which is an mastering called caption

I'm trying to update this catalogItem.caption in each catalogItem in the items array from nsstrings in the second array (tempCaption)

I know to iterate through the arrays but I can't seem to get the syntax right because what I seem to be doing is each catalogItem.caption cycles through each nsstring in the tempCaption array. So it iterates like 49 times instead of the 7 it should. catalogItem.caption all end up being the last item in the tempCaption array.

ViewController.m

-(void)parseUpdateCaptions
{
NSMutableArray *tempCaptions = [NSMutableArray array];
//get server objects
PFQuery *query = [PFQuery queryWithClassName:@"UserPhoto"];
NSArray* parseArray = [query findObjects];
    //fast enum and grab strings and put into tempCaption array
       for (PFObject *parseObject in parseArray) {
        [tempCaptions addObject:[parseObject objectForKey:@"caption"]];
    }


//fast enum through each array and put the capString into the catalogItem.caption slot
//this iterates too much, putting each string into each class object 7 times instead of just putting the nsstring at index 0 in the temCaption array into the catalogItem.caption at index 0, etc. (7 catalogItem objects in total in items array, and 7 nsstrings in tempCaption array)
for (catalogItem in items) {
    for (NSString *capString in tempCaptions) {
            catalogItem.caption = capString;
            DLog(@"catalog: %@",catalogItem.caption);
        }
}

}

if needed - class object header.h

#import <Foundation/Foundation.h>

@interface BBCatalogClass : NSObject


@property (nonatomic, strong) NSData *image;
@property (nonatomic, strong) NSData *carouselImage;
@property (nonatomic, strong) NSString *objectID;
@property (nonatomic, strong) NSString *caption;
@end

Chris Trahey · Accepted Answer · 2012-06-21 14:18:02Z

1

I would try traditional for looping instead of fast enumeration. This will work if I understand you correctly, that the indexes of the two arrays are aligned.

for(int i = 0; i<items.count; i++) {
  catalogItem = [items objectAtIndex:i]; 
  catalogItem.caption = [tempCaptions objectAtIndex:i];
}

edited Jun 21, 2012 at 14:18

answered Jun 21, 2012 at 4:18

Chris Trahey

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2 Comments

BigB Over a year ago

this method worked except i had to change [array objectatindex:i].caption to catalogItem = [items objectAtIndex:i]; catalogItem.caption = [tempCaptions objectAtIndex:i];

Chris Trahey Over a year ago

Cool, expected. I have updated the answer so anyone who stumbles upon this will see it clearly.

Apurv · Accepted Answer · 2012-06-21 04:37:09Z

0

You are iterating with nested for loop. It means total iteration count will be (items.count * tempCaptions.count).

So, either you should fast iterate both in a single loop or you should go with traditional approach as suggested above.

answered Jun 21, 2012 at 4:37

Apurv

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1 Comment

BigB Over a year ago

out of curiosity how would one do this using fast enumeration in a single loop?

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