Convert NSNumber to int in Objective-C

Question

I use [NSNumber numberWithInt:42] or @(42) to convert an int to NSNumber before adding it to an NSDictionary:

int intValue = 42;
NSNumber *numberValue = [NSNumber numberWithInt:intValue];
NSDictionary *dict = @{ @"integer" : numberValue };

When I retrieve the value from the NSDictionary, how can I transform it from NSNumber back to int?

NSNumber *number = dict[@"integer"];
int *intNumber = // ...?

It throws an exception saying casting is required when I do it this way:

int number = (int)dict[@"integer"];

score 207 · Accepted Answer · edited Dec 10 '19 at 04:06

207

Have a look at the documentation. Use the intValue method:

NSNumber *number = [dict objectForKey:@"integer"];
int intValue = [number intValue];

edited Dec 10 '19 at 04:06

pkamb

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answered Aug 24 '10 at 11:28

Felix Kling

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Implicit conversion is now disallowed with ARC. – Alexander Nov 21 '17 at 12:52
basically `[key intValue]` (key is `NSNumber`) – user924 Mar 26 '18 at 11:33

score 62 · Answer 2 · answered Aug 24 '10 at 11:29

62

You should stick to the NSInteger data types when possible. So you'd create the number like that:

NSInteger myValue = 1;
NSNumber *number = [NSNumber numberWithInteger: myValue];

Decoding works with the integerValue method then:

NSInteger value = [number integerValue];

answered Aug 24 '10 at 11:29

Max Seelemann

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Why should he stick to the `NSInteger`? – Iulian Onofrei Dec 19 '14 at 12:24
`NSInteger` is a primitive type thats **much** faster during execution that `NSNumber` which is an object. – Max Seelemann Dec 19 '14 at 20:50
And what is `int`? A primitive too? – Iulian Onofrei Dec 19 '14 at 20:53
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`int` is primitive too, yes. However it's maximum allowed number is less precisely defined. `NSInteger` is essentially just an alias to some primitive integer type that's known to be 32bit on 32bit machines and 64bit on 64bit devices. – Max Seelemann Jan 06 '15 at 10:31
So it's a good idea to use `NSInteger` over `int` in the most cases? – Iulian Onofrei Jan 06 '15 at 12:43
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Yes, Apple suggests to. – Max Seelemann Jan 09 '15 at 16:43
Seelmann, but I guess that if I know the numbers I need are not large, it's ok to use `int` over `NSInteger`, right? – Iulian Onofrei Jan 09 '15 at 17:10
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I'd recommend not guesstimating anything about native number arithmetics. You can sure use `int`, but there is little point in doing so, except for interfacing with cross-platform libs. And even then something like `uint32_t` would be better to use. – Max Seelemann Jan 11 '15 at 13:06
I'm sorry if I'm bothering you, I'm just trying to learn and understand more. I recently started learning Objective C working on a big project and I'm thinking about ways to refactor it. So, it's a good idea to replace `int` with `NSInteger` everywhere possible in the existing project, right? – Iulian Onofrei Jan 11 '15 at 13:37
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Doing that would certainly make it more consistent with platform coding standards, yes. – Max Seelemann Jan 12 '15 at 15:12
Always use NSInteger. – Fattie Aug 14 '15 at 18:28

score 4 · Answer 3 · answered Aug 24 '10 at 11:27

4

Use the NSNumber method intValue

Here is Apple reference documentation

answered Aug 24 '10 at 11:27

rano

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score 1 · Answer 4 · edited Dec 10 '19 at 04:06

1

A less verbose approach:

int number = [dict[@"integer"] intValue];

edited Dec 10 '19 at 04:06

pkamb

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answered Jul 15 '15 at 08:27

baskInEminence

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Giorgio Barchiesi · Answer 5 · 2019-09-27T16:43:24.177

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A tested one-liner:

int number = ((NSNumber*)[dict objectForKey:@"integer"]).intValue;

edited Sep 27 '19 at 16:43

answered Sep 27 '19 at 15:57

Giorgio Barchiesi

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Convert NSNumber to int in Objective-C

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