Question

How should I handle text formatting in iOS? I’m not talking about Currency or Decimal styles. Since iOS doesn’t have setFormat(), it’s kind of complicated.

Two examples of the format I want: 123.456.789-10 and 123.456.789/1000-00.

My aim is to format a text field as the user types. Like any normal site does when, for example, you type a phone number. It doesn’t comes from a model or anything. The user just needs to type the numbers and when necessary I’ll insert the ".","/" or "-".

Answer 1

You can use regular expressions to do formatting, like this:

NSRegularExpression *fmt = [NSRegularExpression
    regularExpressionWithPattern:@"(.{1,3})(.{1,3})(.{1,3})(.{1,2})"
                         options:0
                           error:NULL];
NSMutableString *str = [NSMutableString stringWithString:@"12345678910"];
[fmt replaceMatchesInString:str
                    options:0
                      range:NSMakeRange(0, str.length)
               withTemplate:@"$1.$2.$3-$4"];

This transforms the string into 123.456.789-10

In order to apply this formatting dynamically as users type, create NSRegularExpression *fmt upfront, store it in your UITextFieldDelegate, and use it in your textField:shouldChangeCharactersInRange:replacementString: method.