Format a UITextField for currency - ios

Question

I have a UITextField on my aplication that receives only numeric input from the user. This numeric input represents currency and have the default value of 0.00.
I would like to create something like a mask to format the UITextField as the user enter the numbers. For example:
9 becomes $0,09
99 becomes $0,99
999 becomes $999,99
The code below works great, but as I'm using integer and float values the app will eventually display wrong values afeter a certain point. For example:
999999999 becomes 100000000
That happens because flot and integer aren't precise enough and NSDEcimalNumber should be used. The point is that I can't figure out how to replace my integers and float values to NSDecimalNumber ones.
Does anyone could give me a hand to solve this? I spend some time searching the web for a solution but didn't find that suits my needs and tons of people with the same problem.
Heres the code:
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if (textField.tag == 1){
NSString *cleanCentString = [[textField.text componentsSeparatedByCharactersInSet: [[NSCharacterSet decimalDigitCharacterSet] invertedSet]] componentsJoinedByString:#""];
NSInteger centValue= cleanCentString.integerValue;
if (string.length > 0)
{
centValue = centValue * 10 + string.integerValue;
}
else
{
centValue = centValue / 10;
}
NSNumber *formatedValue;
formatedValue = [[NSNumber alloc] initWithFloat:(float)centValue / 100.0f];
NSNumberFormatter *_currencyFormatter = [[NSNumberFormatter alloc] init];
[_currencyFormatter setNumberStyle:NSNumberFormatterCurrencyStyle];
textField.text = [_currencyFormatter stringFromNumber:formatedValue];
return NO;
}
if (textField.tag == 2){
// Nothing for now
}
return YES;
}

Answer 1

Implement UITextFieldDelegate and add next methods:
Swift:
let currencySign = "$"
// Adds $ before the text, e.g. "1" -> "$1" and allows "." and ","
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
var value = textField.text
var newString = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: string)
var components = newString.componentsSeparatedByCharactersInSet(NSCharacterSet(charactersInString: "1234567890,.").invertedSet)
var decimalString = "".join(components) as NSString
var length = decimalString.length
if length > 0 {
value = "\(currencySign)\(decimalString)"
}
else {
value = ""
}
textField.text = value
}
// Formats final value using current locale, e.g. "130,50" -> "$130", "120.70" -> "$120.70", "5" -> "$5.00"
func textFieldDidEndEditing(textField: UITextField) {
var value = textField.text
var components = value.componentsSeparatedByCharactersInSet(NSCharacterSet(charactersInString: "1234567890,.").invertedSet)
var decimalString = "".join(components) as NSString
let number = NSDecimalNumber(string: decimalString, locale:NSLocale.currentLocale())
var formatter = NSNumberFormatter()
formatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
formatter.locale = NSLocale.currentLocale()
if let formatedValue = formatter.stringFromNumber(number) {
textField.text = formatedValue
}
else {
textField.text = ""
}
}

Answer 2

You can convert integer or double/float value to string by following:
NSString *str = [#(myInt) stringValue];
NSString *str1 = [[NSNumber numberWithFloat:myFloat] stringValue];
After that you can convert string to NSDecimalNumber by many ways. Like:
NSDecimalNumber *number = [NSDecimalNumber decimalNumberWithString:#"100.1"];
NSLog(#"%#", number);
NSDecimalNumber *num = [NSDecimalNumber decimalNumberWithString:#"100.1" locale:NSLocale.currentLocale];
NSLog(#"%#",num);
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
[formatter setLocale:[NSLocale currentLocale]];
NSLog(#"%#", [formatter stringFromNumber:number]);
NSNumberFormatter will help you with the right formatting. Please read apples page for NSDecimalNumber and NSNumberFormatter.
NSNumberFormatter contains a section named"Configuring the Format of Currency". I didn't try it, but it seems something that can help you.
Let me know if this helps.. :)