@"" string type literals for NSNumber

Question

I love the shorthand handling of string literals in Objective C with the @"string" notation. Is there any way to get similar behavior with NSNumbers? I deal with numbers more and it's so tedious having [NSNumber numberWithWhatever:] calls everywhere. Even creating a macro would work, but my knowledge of how best to do that is limited.

As pointed out by rjstelling, this is now a feature in clang. Much rejoicing. Please vote to close, thanks. — rob5408, Jun 20 '12 at 17:52
There's no need to close this. It's a perfectly valid question. Closure is for undesirable questions, where answers need to be prevented. — jscs, Sep 14 '12 at 19:47
You should accept @rjstelling's answer instead though as it is more correct now. — Philippe Sabourin, Sep 26 '13 at 14:41
Hmm, I wonder what the SO perspective on that is. Tilo answered the question as it was at that time so it seems a bit unfair to award it to another person after the facts changed. Like discounting von Neumann because he didn't foresee multi-cores or something. At 1542 views over three years this question isn't exactly even getting used that much. In addition, I think Tilo's answer and JeremyP's improvements could still be useful to someone maybe looking for NSSet literal syntax or NSMutableArray literal syntax workarounds however unlikely they are to show up here looking towards that end. — rob5408, Sep 27 '13 at 07:39

score 32 · Answer 1 · answered Jul 08 '13 at 20:01

32

Since nobody has mentioned this... If you need to wrap a value in an NSNumber, the NSNumber literal syntax is as follows.

int val = 13;
NSNumber *numVal = @(val);

answered Jul 08 '13 at 20:01

Adam Lockhart

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Hi Adam, good point. Even after the new syntax came out this was not immediately obvious to me. – rob5408 Jul 08 '13 at 22:55
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Is there a shorthand for the opposite? A way to get intValue off of an NSNumber? – Rob Aug 09 '13 at 22:31
it works, but is little bit "cryptic" or obvious for me to use it. – kraag22 Feb 27 '14 at 16:12

score 31 · Answer 2 · edited Sep 14 '12 at 19:44

31

As of Clang v3.1 you can now use Objective-C literals.

NSNumber *fortyTwo = @42;             // equivalent to [NSNumber numberWithInt:42]
NSNumber *fortyTwoUnsigned = @42U;    // equivalent to [NSNumber numberWithUnsignedInt:42U]
NSNumber *fortyTwoLong = @42L;        // equivalent to [NSNumber numberWithLong:42L]
NSNumber *fortyTwoLongLong = @42LL;   // equivalent to [NSNumber numberWithLongLong:42LL]

So, answering your specific question:

[Tyler setArms:[[[NSNumber alloc] initWithInt:1] autorelease]];

Can now be written as:

[Tyler setArms:@1];

There are also literals for arrays and dictionaries, but they are beyond the scope of this question.

To take advantage of literals in Xcode you'll need at least version 4.4 -- this comes with Apple's LLVM 4.0 compiler.

edited Sep 14 '12 at 19:44

jscs

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answered Jun 20 '12 at 13:14

Richard Stelling

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Yes, very exciting! Also, I'm going to close this question before a million people tell me I'm an idiot. – rob5408 Jun 20 '12 at 17:50
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@rob5408 no one will think your an idiot, it is a valid question and you asked about it almost 2 years before it was available. You get a +1 from me. – Joe Jul 25 '12 at 18:00
There is no corresponding shortcut for a variable of type NSInteger, float, double, so on? – Shaun Budhram Mar 01 '13 at 22:28

Tilo Prütz · Accepted Answer · 2010-09-22T11:56:21.540

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I'm using a macro like

#define N(x) [NSNumber numberWithInt: x]

wich leads to code like

[N(123) intValue];

update:

One should be aware of the CPU and memory consumption of such a macro. While the @"…" strings are static compiler generated strings of the constant string class (depends on foundation maybe NSConstantString in Cocoa?) the macros create code which is evaluated at runtime and therefore create a new object every time they are called.

edited Sep 22 '10 at 11:56

answered Sep 20 '10 at 12:47

Tilo Prütz

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Slight improvement: `#define N(x) [NSDecimalNumber decimalNumberWithString: @"" #x]`. Will allow you to do things like `N(1.4)` or `N(1E09)` – JeremyP Sep 20 '10 at 13:08
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Yes, but isn't it significant slower? I'm using an `F(x)` macro for floating points which invokes `[NSNumber numberWithDouble: x]`. – Tilo Prütz Sep 20 '10 at 13:17

score 7 · Answer 4 · edited May 23 '17 at 12:34

Xcode 4.4 has introduced the Clang features that rjstelling mentioned for literals for NSNumber, NSArray and NSDictionary. The syntax is simple:

//Number literal
NSNumber *pi = @3.14;

//Array literal
NSArray *primes = @[ @2, @3, @5, @7, @11 ]; //No nil terminator needed

//Dictionary literal
NSDictionary *dict = @{
    @"key1": @42,
    @"key2": @"Another key",
    @3: @"A NSNumber key"
}; //No nil terminator, stored in "key:value," format

@"" string type literals for NSNumber

4 Answers4