Using @[array, of, items] vs [NSArray arrayWithObjects:]

Question

Is there a difference between

NSArray *myArray = @[objectOne, objectTwo, objectThree];

and

NSArray *myArray = [NSArray arrayWithObjects:objectOne, objectTwo, objectThree, nil];

Is one preferred over the other?

possible duplicate of Difference between @[] and [NSArray arrayWithObjects:] — jscs
– jscs, Commented Jan 25, 2013 at 18:47
Sorry, I even searched google and here. Maybe the symbols were messing up the search that is why i wasn't getting anything relevant. — Bot
– Bot, Commented Jan 25, 2013 at 18:57
It's not meant to be a recrimination. Actually, that comment is created by the system on my behalf when I vote to close. — jscs
– jscs, Commented Jan 25, 2013 at 19:26

Martin R · Accepted Answer · 2013-01-25 17:55:20Z

32

They are almost identical, but not completely. The Clang documentation on Objective-C Literals states:

Array literal expressions expand to calls to +[NSArray arrayWithObjects:count:], which validates that all objects are non-nil. The variadic form, +[NSArray arrayWithObjects:] uses nil as an argument list terminator, which can lead to malformed array objects.

So

NSArray *myArray = @[objectOne, objectTwo, objectThree];

would throw a runtime exception if objectTwo == nil, but

NSArray *myArray = [NSArray arrayWithObjects:objectOne, objectTwo, objectThree, nil];

would create an array with one element in that case.

answered Jan 25, 2013 at 17:55

Martin R

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2 Comments

jlehr Over a year ago

+1 This is the correct answer; the difference is subtle, but nevertheless the two are different.

newacct Over a year ago

I'm not sure what "malformed array objects" means, but the arrays would be perfectly fine, just not the length you thought they would be. Also, I sometimes intentionally exploit the nil termination behavior, to have an optional last element that is only included if it is not nil.

DrummerB · Accepted Answer · 2013-01-25 17:51:39Z

-2

No. At compile time the @[...] literals will be changed to arrayWithObjects:

The only difference is that @[...] is only supported in newer versions of the LLVM compiler.

answered Jan 25, 2013 at 17:51

DrummerB

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1 Comment

newacct Over a year ago

No it is arrayWithObjects:count:

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