Convert basic script to Objective C (money formatting)

Question

I\'ve got this basic like script that I need to convert to objective c, it turns big units of money into shortened versions (ie: 1.2m, etc), I\'ve got most of the conversion

Answer 1

Just to improve the solution, a good idea is maybe to subclass the NSNumberFormatter class and override the - (NSString *)stringForObjectValue:(id)anObject method.

Using the code from zardon, I added a statement for the values < 1000 which doesn't format the number.

Here is the code of the method :

/*
    Override the stringForObjectValue method from NSNumberFormatter

    100 -> 100
    1000 -> 1k
    1 000 000 -> 1m
    1 000 000 000 -> 1b
    1 000 000 000 -> 1t
 */
- (NSString *)stringForObjectValue:(id)anObject {

    // If we don't get a NSNumber, we can't create the string
    if (![anObject isKindOfClass:[NSNumber class]]) {
        return nil;
    }

    NSNumberFormatter *nformat = [[NSNumberFormatter alloc] init];

    // Decimal value from the NSObject
    double doubleValue = [anObject doubleValue];

    NSString *stringValue = nil;

    // Abbrevations used
    NSArray *abbrevations = [NSArray arrayWithObjects:@"k", @"m", @"b", @"t", nil] ;

    // If the value is less than 1000, we display directly the value
    if(doubleValue < 1000.0) {
        stringValue = [NSString stringWithFormat: @"%@", [nformat stringFromNumber: [NSNumber numberWithDouble: doubleValue]] ];
    }
    else { // Otherwise we format it as expected
        for (NSString *s in abbrevations) {
            doubleValue /= 1000.0 ;

            if ( doubleValue < 1000.0 ) {

                if ( (long long)doubleValue % (long long) 100 == 0 ) {
                    [nformat setMaximumFractionDigits:0];
                } else {                
                    [nformat setMaximumFractionDigits:2];
                }

                stringValue = [NSString stringWithFormat: @"%@", [nformat stringFromNumber: [NSNumber numberWithDouble: doubleValue]] ];
                NSUInteger stringLen = [stringValue length];

                if ( [stringValue hasSuffix:@".00"] )
                {               
                    // Remove suffix
                    stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-3)];            
                } else if ( [stringValue hasSuffix:@".0"] ) {

                    // Remove suffix
                    stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-2)];

                } else if ( [stringValue hasSuffix:@"0"] ) {

                    // Remove suffix
                    stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-1)];        
                }

                // Add the letter suffix at the end of it
                stringValue = [stringValue stringByAppendingString: s];

                break;
            }   
        }
    }

    [nformat release];

    return stringValue;
}

In the interface we simply add the inheritage statement :

@interface MoneyNumberFormatter : NSNumberFormatter

Hope this helps..

Answer 2

.... Okay, with thanks to the author of the Cocoa Tidbits blog, I believe I have a solution which is much more elegant, faster and doesn't require so much coding; it still needs testing, and it also probably requires a little more editing, but it seems to be much better than my original.

I modified the script a little to make it not show any trailing zeros where relevant;

    NSNumberFormatter *nformat = [[NSNumberFormatter alloc] init];
    [nformat setFormatterBehavior:NSNumberFormatterBehavior10_4];
    [nformat setCurrencySymbol:@"$"];
    [nformat setNumberStyle:NSNumberFormatterCurrencyStyle];
    double doubleValue = 10200;
    NSString *stringValue = nil;
    NSArray *abbrevations = [NSArray arrayWithObjects:@"k", @"m", @"b", @"t", nil] ;

    for (NSString *s in abbrevations)
    {

        doubleValue /= 1000.0 ;

        if ( doubleValue < 1000.0 )
        {

            if ( (long long)doubleValue % (long long) 100 == 0 ) {
                [nformat setMaximumFractionDigits:0];
            } else {                
                [nformat setMaximumFractionDigits:2];
            }

            stringValue = [NSString stringWithFormat: @"%@", [nformat stringFromNumber: [NSNumber numberWithDouble: doubleValue]] ];
            NSUInteger stringLen = [stringValue length];

            if ( [stringValue hasSuffix:@".00"] )
            {               
                // Remove suffix
                stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-3)];            
            } else if ( [stringValue hasSuffix:@".0"] ) {

                // Remove suffix
                stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-2)];

            } else if ( [stringValue hasSuffix:@"0"] ) {

                // Remove suffix
                stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-1)];        
            }


            // Add the letter suffix at the end of it
            stringValue = [stringValue stringByAppendingString: s];

            //stringValue = [NSString stringWithFormat: @"%@%@", [nformat stringFromNumber: [NSNumber numberWithDouble: doubleValue]]  , s] ;
            break ;
        }   
    } 

    NSLog(@"Cash = %@", stringValue);