Pretty good (North America only) phone number UITextField

gistfile1.m

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    if (textField == self.myPhoneTextField) {
        NSString *newText = [textField.text stringByReplacingCharactersInRange:range withString:string];
        BOOL deleting = [newText length] < [textField.text length];
        
        NSString *stripppedNumber = [newText stringByReplacingOccurrencesOfString:@"[^0-9]" withString:@"" options:NSRegularExpressionSearch range:NSMakeRange(0, [newText length])];
        NSUInteger digits = [stripppedNumber length];
        
        if (digits > 10)
            stripppedNumber = [stripppedNumber substringToIndex:10];
        
        UITextRange *selectedRange = [textField selectedTextRange];
        NSInteger oldLength = [textField.text length];

        if (digits == 0)
            textField.text = @"";
        else if (digits < 3 || (digits == 3 && deleting))
            textField.text = [NSString stringWithFormat:@"(%@", stripppedNumber];
        else if (digits < 6 || (digits == 6 && deleting))
            textField.text = [NSString stringWithFormat:@"(%@) %@", [stripppedNumber substringToIndex:3], [stripppedNumber substringFromIndex:3]];
        else
            textField.text = [NSString stringWithFormat:@"(%@) %@-%@", [stripppedNumber substringToIndex:3], [stripppedNumber substringWithRange:NSMakeRange(3, 3)], [stripppedNumber substringFromIndex:6]];
        
        UITextPosition *newPosition = [textField positionFromPosition:selectedRange.start offset:[textField.text length] - oldLength + range.length];
        UITextRange *newRange = [textField textRangeFromPosition:newPosition toPosition:newPosition];
        [textField setSelectedTextRange:newRange];
        
        return NO;
    }
    
    return YES;
}