Objective-C - How To Remove Characters From a String?

Question

I have a UILable that has a formatted String (formatted for currency), so there is a dollar sign, $21.34.

In the core data entity the attribute is of a type double, I am using an NSDecimalNumber to save to the database.

    self.purchase.name = self.nameTextField.text;
    NSString *string = self.amountLabel.text
    NSDecimalNumber *newAmount = [[NSDecimalNumber alloc] initWithString:string];
    NSLog(@"%@", string); // THIS RETURNS NaN, because of dollar sign i think

    NSManagedObjectContext *context = self.purchase.managedObjectContext;

    NSError *error = nil;
    if (![context save:&error]) 
    {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

Anyway, I need this to not be NaN, so my thinking is to remove the dollar sign, but i do not know how to do that, or perhaps there is a better way to accomplish my goal.

Answer 1

Try this:

NSDecimalNumber *newAmount = [[NSDecimalNumber alloc] initWithString:[string substringFromIndex:1]];

Answer 2

Really you should have your value which is a simple number, like a float if dealing in currency. Then you should have a string that represents your value. You could use an NSNumberFormatter to get from the value to the string, like you say you have, but you shouldn't be relying on the string as your only source of that value.

Also, NSDecimalNumber is probably overkill for representing something like currency. NSDecimalNumber is better suited for dealing with numbers in scientific notation.

A simple NSNumber object will be good enough for working with currency, using something like numberWithDouble:.

Answer 3

    NSString* cleanedString = [costString stringByTrimmingCharactersInSet: [NSCharacterSet symbolCharacterSet]];

Is a lot more robust than the one above (and I think it will handle commas, too)

Answer 4

OK, so i ended up using this code and it works for me

        NSString *inString = self.amountLabel.text;
    NSMutableString *outString = [NSMutableString stringWithCapacity:inString.length];

    NSScanner *scanner = [NSScanner scannerWithString:inString];
    NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:@".0123456789"];

    while ([scanner isAtEnd] == NO)
    {
        NSString *buffer;
        if ([scanner scanCharactersFromSet:numbers intoString:&buffer])
        {
            [outString appendString:buffer];
        }
        else {
            [scanner setScanLocation:([scanner scanLocation] + 1)];
        }

    }
    NSLog(@"%@", outString);
    NSDecimalNumber *amount = [NSDecimalNumber decimalNumberWithString:outString];

    self.purchase.amount = amount;

Answer 5

if you need to remove the $ sign...why not just do the following before dealing with the number.

NSString *newStringValue = [inputString stringByReplacingOccurrencesOfString:@"$" withString:@""];