Question

I’d like to let a string change letters to lowercase or uppercase randomly(in Xcode).
for example: “example” to “ExaMpLe” or “eXAMPle” or ExAmPlE” or something else like this randomly..
hot can i solve this?

thanks

Answer 1

NSString has both a lowercaseString and uppercaseString method. You can iterate over the characters in a string as a sequence of substrings, using some random source to call the appropriate lower/upper case on each of them, collecting the result. Something like…

NSMutableString result = [NSMutableString string];
for (NSUInteger i = 0; i < [myString length]; i++)
{
  NSString *substring = [myString substringWithRange:NSMakeRange(i, 1)];
  [result appendString:(rand() % 2) ? [substring lowercaseString]
                                    : [substring uppercaseString]];
}

You may prefer a better source of entropy than rand, but it’ll do for an example (don’t forget to seed it if you use this case as is). If the strings are large, you can do it in-place on an NSMutableString.