问题

I have seen

NSArray *objectsToShare = @[objects];

when looking at some example code.

What is the meaning of @[objects] here ?

回答1:

NSArray *objectsToShare = @[objects];

is the same as

NSArray *objectsToShare = [NSArray arrayWithObjects:objects count:count];

回答2:

It is also known as Literals in Objective-C

Examples
Immutable array expression:
NSArray *array = @[ @"Hello", NSApp, [NSNumber numberWithInt:42] ];

When using Apple LLVM compiler 4.0 or later, arrays, dictionaries, and numbers (NSArray, NSDictionary, NSNumber classes) can also be created using literal syntax instead of methods.[22] Literal syntax uses the @ symbol combined with [], {}, (), .

Example without literals:

NSArray *myArray = [NSArray arrayWithObject:someObject];
NSDictionary *myDictionary = [NSDictionary dictionaryWithObject:someObject forKey:@"key"];
NSNumber *myNumber = [NSNumber numberWithInt:myInt];

Example with literals:

NSArray *myArray = @[ someObject ];
NSDictionary *myDictionary = @{ @"key" : someObject };
NSNumber *myNumber = @(myInt);


objc-at-expression : '@' (string-literal | encode-literal | selector-literal | protocol-literal | object-literal)
                   ;

object-literal : ('+' | '-')? numeric-constant
               | character-constant
               | boolean-constant
               | array-literal
               | dictionary-literal
               ;

boolean-constant : '__objc_yes' | '__objc_no' | 'true' | 'false'  /* boolean keywords. */
                 ;

array-literal : '[' assignment-expression-list ']'
              ;

assignment-expression-list : assignment-expression (',' assignment-expression-list)?
                           | /* empty */
                           ;

dictionary-literal : '{' key-value-list '}'
                   ;

key-value-list : key-value-pair (',' key-value-list)?
               | /* empty */
               ;

key-value-pair : assignment-expression ':' assignment-expression
               ;

For more info Read this Tutorial

回答3:

It makes a array with one object thats the object "objects"

回答4:

It is a new feature added to the LLVM compiler. You can create an array with

NSArray *array = @[object1, ...];

Note that you cannot create a mutable array and that you do not need to end the list of objects with nil. Watch the WWDC 2012 video "What's New in LLVM".

来源：https://stackoverflow.com/questions/15635630/what-is-the-use-of-in-objective-c

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