how to use stringWithFormat to dynamically add hyphens into my string

Hi just wondering if it is possible, as the user is entering a string of numbers to dynamically add a hyphen every 5th character of the string...

any help would be greatly appr开发者_开发技巧eciated.

Try this code.

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    NSString *separator = @"-";
    int seperatorInterval = 5;
    NSString *originalString = [textField.text stringByReplacingOccurrencesOfString:separator withString:@""];

    if (![originalString isEqualToString:@""] && ![string isEqualToString:@""]) {

        NSString *lastChar = [textField.text substringFromIndex:[textField.text length] - 1];
        int modulus = [originalString length] % seperatorInterval;

        if (![lastChar isEqualToString:separator] && modulus == 0) {

            textField.text = [textField.text stringByAppendingString:separator];
        }
    }

    return YES;
}

Assuming you are using a UITextField for input, you can use the UITextFieldTextDidChangeNotification action to respond each time the text is modified. A quick and rough example:

- (IBAction)textChanged:(UITextField*)sender
{
    NSString* curText = sender.text;

    //when checking the length, you need to exclude hyphens from the count
    //which is currently not being done (thanks @titaniumdecoy)
    if([curText length] % 5 == 0)
    {
        sender.text = [curText stringByAppendingString:@"-"];
    }
}

Just declare and alloc a 2 strings. Store the numbers in one string(str 1) and count the string length every entry. Check when the string lenght will four digit, perform

str2 = [str1 appendByString:@"`"];

now str1 = str2;

again repeat this process in loop with increment of 4 digit.

Hopes it will help.

Just a concept try to make substrings of each 5 characters then append a hyphen to these then concatenate each one. for this you need to make an array of substrings.use this logical function

-(NSString *)makeMyString:(NSString *)stringA
{
NSMutableArray *tempArray1=[NSMutableArray array];
    //NSString *s=@"12345123451234512";
       NSString *s=stringA;
    BOOL flag=YES;
    while(flag)
    {
        NSString *str;
        if([s length]>=5)
          str=[s substringWithRange:NSMakeRange(0,5)];
        else 
            str=s;
        [tempArray1 addObject:str];
        str=nil;
        if([s length]>=5)
          s=[s substringWithRange:NSMakeRange(5,([s length]-5))];
        else 
            s=@"";
        if([s isEqualToString:@""])
            flag=NO;
    }

    NSString *makeString=@"";
    for(int i=0;i<[tempArray1 count];i++)
    {
        if([[tempArray1 objectAtIndex:i] length]==5)
          makeString =[NSString stringWithFormat:@"%@%@`",makeString,[tempArray1 objectAtIndex:i]];
        else {
             makeString =[NSString stringWithFormat:@"%@%@",makeString,[tempArray1 objectAtIndex:i]];
        }

    }
    NSLog(@"%@",makeString);
return makeString;
}