Format a UITextField for currency

问题:

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; } 

回答1:

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.. :)

回答2:

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 = ""         } } 

文章来源: Format a UITextField for currency