Iterating over object properties

Question

I'm working with lots of code that looks like this:

-(void)switchToPercent{
    int tmp;

    tmp = (statisticsObject.idag3_orig != 0) ? statisticsObject.idag3_orig : [self compareValue:statisticsObject.idag2 withValue:statisticsObject.idag3];
    statisticsView.idag3.text = [NSString stringWithFormat:@"%i", tmp];

    tmp = (statisticsObject.igar3_orig != 0) ? statisticsObject.igar3_orig : [self compareValue:statisticsObject.igar2 withValue:statisticsObject.igar3];
    statisticsView.igar3.text = [NSString stringWithFormat:@"%i", tmp];

    tmp = (statisticsObject.veckan3_orig != 0) ? statisticsObject.veckan3_orig : [self compareValue:statisticsObject.veckan2 withValue:statisticsObject.veckan3];
    statisticsView.veckan3.text = [NSString stringWithFormat:@"%i", tmp];

    tmp = (statisticsObject.manaden3_orig != 0) ? statisticsObject.manaden3_orig : [self compareValue:statisticsObject.manaden2 withValue:statisticsObject.manaden3];
    statisticsView.manaden3.text = [NSString stringWithFormat:@"%i", tmp];

    tmp = (statisticsObject.kvartalet3_orig != 0) ? statisticsObject.kvartalet3_orig : [self compareValue:statisticsObject.kvartalet2 withValue:statisticsObject.kvartalet3];
    statisticsView.kvartalet3.text = [NSString stringWithFormat:@"%i", tmp];

    tmp = (statisticsObject.aret3_orig != 0) ? statisticsObject.aret3_orig : [self compareValue:statisticsObject.aret2 withValue:statisticsObject.aret3];
    statisticsView.aret3.text = [NSString stringWithFormat:@"%i", tmp];

    tmp = (statisticsObject.r123_orig != 0) ? statisticsObject.r123_orig : [self compareValue:statisticsObject.r122 withValue:statisticsObject.r123];
    statisticsView.r123.text = [NSString stringWithFormat:@"%i", tmp];

    [self formatText:statisticsView.idag3];
    [self formatText:statisticsView.igar3];
    [self formatText:statisticsView.veckan3];
    [self formatText:statisticsView.manaden3];
    [self formatText:statisticsView.kvartalet3];
    [self formatText:statisticsView.aret3];
    [self formatText:statisticsView.r123];
}

I'm trying to remove the repetition as much as I can. Originally, the business logic was repeated once for each of the properties shown, but I've moved that into a method named compareValue:withValue:. I've also introduced the conditional operator to remove larger ifelse blocks. I imagine the next step is to reduce the seven chunks of code into one, and iterate over a list of keywords, but how?

Answer 1

I can't really judge if it's a good idea, but one way could be creating an NSArray (or NSSet) containing NSDictionaries with the keypaths that should be compared, and then enumerating through that. Something like this:

#define keyOriginal = "original"
#define keyComparisonItem1 = "comparisonItem1"
#define keyComparisonItem2 = "comparisonItem2"

    NSMutableArray * evaluations = [NSMutableArray array];

    [evaluations addObject:@{keyOriginal : @"idag3_orig", keyComparisonItem1 : @"idag2", keyComparisonItem2 : @"idag3"}];
    [evaluations addObject:@{keyOriginal : @"igar3_orig", keyComparisonItem1 : @"igar2", keyComparisonItem2 : @"igar3"}];
        // and so on...

    for (NSDictionary * evaluation in evaluations) {

        if ([statisticsObject valueForKey:keyOriginal] != 0) {
            tmp = (int)[statisticsObject valueForKey:keyOriginal];
        } else {

            tmp = [self compareValue:[statisticsObject valueForKey:keyComparisonItem1]
                           withValue:[statisticsObject valueForKey:keyComparisonItem2]];
        }

        [self formatText:[statisticsView valueForKey:keyOriginal]];

    }