CODEWITHSUNDEEP
iphoneobjective-ciosnsnumber
Besi
Besi

Reputation: 22959

How to combine the advantages of `int` and `NSInteger`

A seemingly simple question: Can I have some sort of Number object, which can be nil but which I can assign like a primitive int:

like this: 

NSNumber *n = nil; 
n = 3; 

if(n == nil){ 
    // some actions... 
} else if (n == 1){ 
    // some actions... 
} else { 
    // some actions... 
}

Thanks for your input

Upvotes: 2

Views: 196

Answers (4)

EmptyStack
EmptyStack

Reputation: 51374

The answer is NO. If the variable is an object you can either assign another object,

n = anotherNSNumber;

or, set the value by using properties or by methods,

n = [NSNumber numberWithInt:3];

and, compare the object with another object, 

if (n == anotherNSNumber) // Checks the reference

or compare its value by using properties/methods,

if (([n intValue] == 3) || ([n intValue] == [anotherNSNumber intValue]))

Upvotes: 6

aLevelOfIndirection
aLevelOfIndirection

Reputation: 3522

The short answer as others have mentioned is "No".
But the following slight modification to you code will achieve a similar result:

NSNumber *nObject = [NSNumber numberWithInt:3]; 
int n = nObject.intValue; // Zero if nObject is nil

if(nObject == nil){ 
    // some actions... 
} else if (n == 1){ 
    // some actions... 
} else { 
    // some actions... 
}

Upvotes: 3

Chaitanya Gupta
Chaitanya Gupta

Reputation: 4053

No, you can't. The reason for that is that nil is a pointer to the address 0x0 i.e. nil == 0. So you won't be able to disambiguate between 0 and nil.

Not to mention the fact they are also supposed to be different types. nil is used as a pointer whereas a number like 0 or 3 is a scalar.

nil is defined as 

#define nil NULL

A typical definition of NULL goes like this:

#define NULL ((void *)0)

Upvotes: 1

Abizern
Abizern

Reputation: 150785

Not the way you think you can. No.

when you say:

NSNumber *n = nil;

what you are saying is declare a pointer that points to an NSNumber object, but for now have it point to nil This is okay; because what you might do later is to get a pointer to an NSNumber object and then assign it to this variable so that n is then a pointer no a valid NSNumber object.

With your next line:

n = 3;

You are not assigning a value to the object, but you are saying that n points to the address 3. Which isn't an address and which doesn't contain an object.

Upvotes: 1

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