Special way of representing array in objective-c

Question

I have seen in many places over the net and even in apple documentation when an array is represented in the following format:

@[obj1,obj2]

For eg; In predicate programming guide there is a statement like this:

NSCompoundPredicate *predicate = [NSCompoundPredicate andPredicateWithSubpredicates:@[greaterThanPredicate, lessThanPredicate]];

But when I write the same in code , i get an 'unexpected @ in program' (as expected) compiler error. Is this just a way of representing arrays or am i missing something?

Answer 1

This is a relatively new syntax, it is available only with Xcode that includes clang 3.3 or newer.

This

@[greaterThanPredicate, lessThanPredicate]

is logically equivalent^* to this:

[NSArray arrayWithObjects:greaterThanPredicate, lessThanPredicate, nil]

You can always replace the new syntax with the old one without losing functionality.

EDIT (in response to a comment by Nikolai Ruhe) Apple has a different version scheme than the open source version. The correct version numbers that introduced the feature are: Apple 4.0, clang 3.1.

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^* Under the hood the array initializer of the new syntax is transformed to a call of arrayWithObjects:count:. Thanks to newacct for the correction.