How to convert an NSString into an NSNumber

How can I convert a `NSString` containing a number of any primitive data type (e.g. `int`, `float`, `char`, `unsigned int`, etc.)? The problem is, I don't know which number type the string will contain at runtime.

I have an idea how to do it, but I'm not sure if this works with any type, also unsigned and floating point values:

long long scannedNumber;
NSScanner *scanner = [NSScanner scannerWithString:aString];
[scanner scanLongLong:&scannedNumber];
NSNumber *number = [NSNumber numberWithLongLong: scannedNumber];

Thanks for the help.

You can use `-[NSString integerValue]`, `-[NSString floatValue]`, etc. However, the correct (locale-sensitive, etc.) way to do this is to use `-[NSNumberFormatter numberFromString:]` which will give you an NSNumber converted from the appropriate locale and given the settings of the `NSNumberFormatter` (including whether it will allow floating point values).

Here's a working sample of NSNumberFormatter reading localized number NSString (xCode 3.2.4, osX 10.6), to save others the hours I've just spent messing around. Beware: while it can handle trailing blanks ("8,765.4 " works), this cannot handle leading white space and this cannot handle stray text characters. (Bad input strings: " 8" and "8q" and "8 q".)

NSString *tempStr = @"8,765.4";
// localization allows other thousands separators, also.
NSNumberFormatter * myNumFormatter = [[NSNumberFormatter alloc] init];
[myNumFormatter setLocale:[NSLocale currentLocale]]; // happen by default?
[myNumFormatter setFormatterBehavior:NSNumberFormatterBehavior10_4];
// next line is very important!
[myNumFormatter setNumberStyle:NSNumberFormatterDecimalStyle]; // crucial

NSNumber *tempNum = [myNumFormatter numberFromString:tempStr];
NSLog(@"string '%@' gives NSNumber '%@' with intValue '%i'",
tempStr, tempNum, [tempNum intValue]);
[myNumFormatter release]; // good citizen

If you know that you receive integers, you could use:

NSString* val = @"12";
[NSNumber numberWithInt:[val intValue]];

What about C's standard `atoi`?

int num = atoi([scannedNumber cStringUsingEncoding:NSUTF8StringEncoding]);

Do you think there are any caveats?

You can also do this:

NSNumber *number = @([dictionary[@"id"] intValue]]);

Have fun!

I think NSDecimalNumber will do it:

Example:

NSNumber *theNumber = [NSDecimalNumber decimalNumberWithString:[stringVariable text]]];

NSDecimalNumber is a subclass of NSNumber, so implicit casting allowed.

NSDecimalNumber *myNumber = [NSDecimalNumber decimalNumberWithString:@"123.45"];
NSLog(@"My Number : %@",myNumber);

I wanted to convert a string to a double. This above answer didn't quite work for me. But this did:

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All I pretty much did was:

double myDouble = [myString doubleValue];

For strings starting with integers, e.g., `@"123"`, `@"456 ft"`, `@"7.89"`, etc., use [`-[NSString integerValue]`][1].

So, `@([@"12.8 lbs" integerValue])` is like doing `[NSNumber numberWithInteger:12]`.


[1]:

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