CODEWITHSUNDEEP
iphoneobjective-c
liv a
liv a

Reputation: 3340

A tough one truly for the masters of objective-c

I have a code that is pretty much the same the only thing that changes is the property the code "works" on for example

-(void) removeItemsBelowPrice:(NSInteger)p_minimumPrice andAbove:(NSInteger)p_maximumPrice
{
    for( int itemIdx = self.itemsList.count-1; itemIdx >= 0 ; itemIdx--)
    {
        if(((BasicItem*)self.itemsList[itemIdx]).price < p_minimumPrice ||
           ((BasicItem*)self.itemsList[itemIdx]).price > p_maximumPrice)
        {
            [self.itemsList removeObjectAtIndex:itemIdx];
        }
    }
}

so for the property amountInStorage, I'd have the same function duplicated and change the property from price to amountInStorage, i was wondering if there is a way to write a generic function that can receive the property to work on, if possible can this property be of different types

thanks.

Upvotes: 1

Views: 112

Answers (2)

Tam&#225;s Zahola
Tam&#225;s Zahola

Reputation: 9311

Yes, you can do it with NSPredicate:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(YOUR_PROPERTY > LOWER_LIMIT) AND (YOUR_PROPERTY < UPPER_LIMIT)"];
[yourArray filteredArrayUsingPredicate:predicate]

Let's see some untested example code:

-(NSArray*)filterArray:(NSArray*)array byProperty:(NSString*)property lowerLimit:(double)lowerLimit upperLimit:(double)upperLimit{
    return [array filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:[NSString stringWithFormat:@"(%@ >= %g) AND (%@ <= %g)",property,lowerLimit,property,upperLimit]]];
}

Upvotes: 4

trojanfoe
trojanfoe

Reputation: 122391

You are modifying the collection class while enumerating it, which you cannot do (this issue occurs in many languages, not just Objective-C).

Use this technique instead, which first finds all the objects to remove then removes them:

NSIndexSet *indexes = [self.itemList indexesOfObjectsPassingTest:^(id obj, NSUInteger idx, BOOL *stop) {
    BasicItem *basicItem = (BasicItem *)obj;
    return basicItem.price < p_minimumPrice || basicItem.price > p_maximumPrice;
}];
[self.itemList removeObjectsAtIndexes:indexes];

Upvotes: 2

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