dynamic string format with NSString stringWithFormat

Question

I\'ve been trying to make a dynamic string format so that through user options precision or padding could be somewhat user defined.

An example includes, the padding of

Answer 1

Use two steps:

    NSString* hourString=nil;
    if(...){
         hourString=[NSString stringWithFormat:@"%i", hour];
    }else{
         hourString=[NSString stringWithFormat:@"%02i", hour];
    }
    NSString* result=[NSString stringWithFormat:@"Hour: %@", hourString];

The following is considered a bad practice:

    NSString* formatString=nil;
    if(...){
         formatString=@"Hour: %i";
    }else{
         formatString=@"Hour: %02i";
    }
    NSString* result=[NSString stringWithFormat:formatString, hour];

because it's very dangerous to have a variable formatString, which can be used in many types of cracker attacks.