CODEWITHSUNDEEP
iosobjective-ciphonensmutablearray
Pradeep Reddy Kypa
Pradeep Reddy Kypa

Reputation: 4022

How to check if an NSArray contains any object at a particular index?

I am trying to check an NSArray if it contains any object at any particular index and upon checking it i want to insert the object at that particular index if it is empty. Any idea on how to do this?

Upvotes: 1

Views: 5157

Answers (1)

justin
justin

Reputation: 104718

NSArray does not contain nil values; objectAtIndex: will never return nil. it is an error to add nil to the collection.

To accomplish your task, you could use a placeholder object such as [NSNull null] as well as querying the array's count. Of course, you will need an NSMutableArray to actually perform mutations (e.g. replace or insert).

On OS X, you could use NSPointerArray to represent a collection which contains nil elements.

Example using NSNull:

const NSUInteger idx = ...;
NSMutableArray * array = ...;

if ([NSNull null] == [array objectAtIndex:idx]) {
  [array replaceObjectAtIndex:idx withObject:someObject];
}

Upvotes: 13

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