Formatting a dollar amount in real time

Question

I am working on an iOS app that requires the user to enter a dollar amount. It needs to allow them to enter dollars and cents with a max value of $9999.99

I want it to work like this: there is a textfield that displays: "$0.00" to type $5.25 the input will change with each key press. so it would look like this: '5' is pressed, display: $0.05 '2' is pressed, display: $0.52 '5' is pressed, display: $5.25

I have tried to make this work a number of different ways but all present the problem. Using NSNumberformatter does not work correctly. Using a link list or array will not work if the user presses backspace, and I really do not want to implement a stack as I fear it will be too time consuming. Please advise on how I should approach this problem. Thanks

I think you'd just format the string brute force and display it, updating after each button push. — Hot Licks, Feb 19 '13 at 20:07
NSNumberFormatter would work fine for this (this is a common thing in many apps). Perhaps post how you tried to use it, and someone can point out the mistake. — Firoze Lafeer, Feb 19 '13 at 20:10
Does this help? http://stackoverflow.com/questions/2388448/re-apply-currency-formatting-to-a-uitextfield-on-a-change-event — Jonesopolis, Feb 19 '13 at 20:12

score 1 · Accepted Answer · answered Feb 19 '13 at 20:37

This is just an indicative example that shows how to do it. You should study this code and readapt it to your situation. Try it:

@autoreleasepool
{
    // Here I create the formatter and I set the format. You do this faster with setFormat: .
    NSNumberFormatter* formatter=[[NSNumberFormatter alloc]init];
    formatter.numberStyle= NSNumberFormatterCurrencyStyle;
    formatter.maximumIntegerDigits=6;
    formatter.maximumFractionDigits=2;
    formatter.currencySymbol= @"$";
    formatter.currencyDecimalSeparator= @".";
    formatter.currencyGroupingSeparator= @",";
    formatter.positivePrefix=@"";

    NSArray* numbers= @[ @1 ,@2 ,@3 ,@4, @5, @6, @7, @8  ];
    // These are the inserted numbers, you should change the code in a way that
    // every number is taken in input from the text field.
    float number=0.0f;
    for(NSUInteger i=0;i<8;i++)
    {
        // It just simulates what happens if the user types the numbers in the array.
        number= [numbers[i] floatValue] * 1.0e-2 + number*10;
        NSLog(@"%@",[formatter stringFromNumber: @(number)]);
    }
}

Tanner is not trying to format a number in dollars and cents. He wants a UITextField that will dynamically format as the user types and deletes characters. — Geoff Hackworth, Feb 19 '13 at 20:55
Is enough to readapt this code to the string taken in input from the text field. — Ramy Al Zuhouri, Feb 19 '13 at 21:11

score 0 · Answer 2 · answered Feb 19 '13 at 20:53

0

NSString* formattedAmount = [NSString stringWithFormat:@"$%01d.%02d",dollars,cents];

answered Feb 19 '13 at 20:53

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Formatting a dollar amount in real time

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