CODEWITHSUNDEEP
iphoneobjective-ciosxcode
Ahan Malhotra
Ahan Malhotra

Reputation: 185

Set Value To Zero In Array

In my app I use the following code to set a value of an array to zero:

 [[records objectAtIndex:prizenotify] setValue:nil forKey:@"marbles"];
    NSError *error;
    [_managedObjectContext save:&error]; //Save

But, It crashes my code. Am I coding this correctly? Marbles is an NSNumber.

Thanks!

Upvotes: 0

Views: 393

Answers (4)

Regexident
Regexident

Reputation: 29552

[[records objectAtIndex:prizenotify] setValue:[NSNumber numberWithInteger:0] forKey:@"marbles"];

Or in modern Objective-C:

[records[prizenotify] setValue:@0 forKey:@"marbles"];

Upvotes: 2

Oliver
Oliver

Reputation: 23510

Make sure that [records objectAtIndex:prizenotify] object is a NSMutableDictionary.

To be sure, test :

[[((NSDictionary*)[records objectAtIndex:prizenotify]) mutableCopy] setValue:[NSNumber numberWithInteger:0] forKey:@"marbles"];

if this one works, the problem is that you just have a NSDictionary (not mutable).

If you have a NSMutableDictionary for sure :

  • If you want to set the value to zero, call :

    [[records objectAtIndex:prizenotify] setValue:[NSNumber numberWithInteger:0] forKey:@"marbles"];

  • If you want to delete the 'marbles' key from the dictionary, call :

    [[records objectAtIndex:prizenotify] removeObjectForKey:@"marbles"];

Upvotes: 0

jbat100
jbat100

Reputation: 16827

Although I would choose Sean's solution ([NSNull null]) as the simplest solution, there is also the NSPointerArray class (which specifically answers your question). Here's the overview:

NSPointerArray is a mutable collection modeled after NSArray but it can also hold NULL values, which can be inserted or extracted (and which contribute to the object’s count). Moreover, unlike traditional arrays, you can set the count of the array directly. In a garbage collected environment, if you specify a zeroing weak memory configuration, if an element is collected it is replaced by a NULL value.

Upvotes: 0

Sean
Sean

Reputation: 5820

If you're looking to set a nil-esque value, you can use [NSNull null] to insert null/nil values into a collection class like NSArray.

Upvotes: 0

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