NSNumberFormatter with comma decimal separator

问题:

I tried to convert an NSString like "12000.54" into "12.000,54". I wrote an NSNumberFormatter instance.

NSNumberFormatter *formatter = [[[NSNumberFormatter alloc] init] autorelease];
[formatter setFormatterBehavior:NSNumberFormatterBehavior10_4];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
[formatter setGroupingSeparator:@"."];
[formatter setDecimalSeparator:@","];

But when I NSLog this :

NSLog(@"%@",[formatter stringFromNumber:[formatter numberFromString:value]]);

It prints null value. If I change my comma with a point it's working correctly. I just would like to be able to put what I want for my separators field (comma, point, slash, etc ...) and I have different outputs : 12/000,54 12.000.54 12,000,54 for example.

Do you know how I can handle this ?

回答1:

I would recommend not hardcoding the separator to ensure the right separator behavior based on the iPhone locale setting. The easiest way to to this is:

using objective-c

NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc]init];
numberFormatter.locale = [NSLocale currentLocale];// this ensures the right separator behavior
numberFormatter.numberStyle = NSNumberFormatterDecimalStyle;
numberFormatter.usesGroupingSeparator = YES;

// example for writing the number object into a label
cell.finalValueLabel.text = [NSString StringWithFormat:@"%@", [numberFormatter stringForObjectValue:numberFromString]]; // your var name is not well chosen

using SWIFT 3

 let formatter = NumberFormatter()
 formatter.locale = NSLocale.current // this ensures the right separator behavior
 formatter.numberStyle = NumberFormatter.Style.decimal
 formatter.usesGroupingSeparator = true

 // example for writing the number object into a label
 // your variable "numberFromString" needs to be a NSNumber object
 finalValueLabel.text = formatter.string(from: numberFromString)! // your var name is not well chosen

and I would not use the var-name "numberFromString" because it is an NSNumberFormatter method. Good luck!

回答2:

So the question is valid : I'm answering it myself :)

I have a decimal value read from sqlite (e.g 12000 or 12000.54) directly transformed into NSString. I have to use different separator at some point in my code.

NSNumberFormatter *formatter = [[[NSNumberFormatter alloc] init] autorelease];
[formatter setFormatterBehavior:NSNumberFormatterBehavior10_4];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
[formatter setGroupingSeparator:@""];
[formatter setDecimalSeparator:@"."];

// Decimal values read from any db are always written with no grouping separator and a comma for decimal.

NSNumber *numberFromString = [formatter numberFromString:@"12000.54"]];

[formatter setGroupingSeparator:@" "]; // Whatever you want here
[formatter setDecimalSeparator:@","]; // Whatever you want here

NSString *finalValue = [formatter stringFromNumber:numberFromString];

NSLog(@"%@",finalValue); // Print 12 000,54

Problem solved.

回答3:

The simplest solution I recently found is:

NSString *localizedString = [NSString localizedStringWithFormat:@"%@", @1234567];

Also works with ints:

NSString *localizedString = [NSString localizedStringWithFormat:@"%d", 1234567];

Verified in Xcode 6 playground. But docs say this function has always existed.

回答4:

NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
[numberFormatter setNumberStyle:NSNumberFormatterDecimalStyle];
numberFormatter.usesGroupingSeparator = YES;
[numberFormatter setMaximumFractionDigits:2];
[numberFormatter setMinimumFractionDigits:2];
NSString *formattedNumberString = [numberFormatter stringFromNumber:@122344.00];`

This wll fix your rounding up problem if you are dealing with decimal points.

回答5:

For currency use...

let numberFormatter = NumberFormatter()

// Produces symbol (i.e. "$ " for en_US_POSIX) and decimal formatting
numberFormatter.numberStyle = .currency

// Produces commas; i.e. "1,234"
numberFormatter.usesGroupingSeparator = true
numberFormatter.groupingSize = 3

Example usage:

let value: Double = 12345.6789
numberFormatter.string(from: value as NSNumber)

yields...

"$ 12,345.68"

as one would expect