addObject and initWithObjects difference for arrays in Objective C

Question

NSMutableArray *firstColumn = [[NSMutableArray alloc]init];
[firstColumn addObject:tile1];
[firstColumn addObject:tile2];
[firstColumn addObject:tile3];

When you use addObject on to a NSMUtableArray, we do not add "nil" but when initWithObjects is used, there is a "nil" parameter in the statement.

What does nil signify? Does it mention that it's reaching the end of the Array ?

 NSMutableArray *thirdCoulmn =[[NSMutableArray alloc] initWithObjects:tile7,tile8,tile9,nil];

Yeah, it's a sentinel value. varargs functions either need a sentinal value or some other way to keep track (eg printf uses the format string) — sapi, Sep 07 '14 at 06:58

score 2 · Accepted Answer · edited May 23 '17 at 10:33

2

As mentioned in the comment, this doesn't have to do with NSMutableArray, but the vargs features (variable arguments). It uses a sentinel value, nil, to determine the end of the argument list.

Search for vargs to learn more about this feature.

edited May 23 '17 at 10:33

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answered Sep 07 '14 at 07:00

Mazyod

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addObject and initWithObjects difference for arrays in Objective C

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