Question

I don’t have much experience in objective-c, sorry if this is really obvious.

What I need is to split a NSString into tokens. The tokens are separated by spaces or by another sign (not a letter). The catch is that I want to keep the separators except when they are spaces.

Example phrase: “a b c,d’s, e f.” from this I would like to get:

"a"
"b"
"c"
","
"d"
"'"
"s"
","
"e"
"f"
"."

With this code:

NSMutableCharacterSet *separators = [NSMutableCharacterSet punctuationCharacterSet];
[separators formUnionWithCharacterSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

NSArray *parse_array = [intext componentsSeparatedByCharactersInSet:separators];

I get only the letters. If I just filter the whitespaces and NL I get the signs together with the letters. What i need is to perform two parsings in sequence (first the whitespaces and Nl and then the punctuation), but I really don’t know how to do it in objective-c. Can anyone give me a hint?

Thanks!

Answer 1

Well, you could do something like this to remove all the whitespace from a string:

NSArray * t = [string componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
string = [t componentsJoinedByString:@""];

Then you could just iterate over the characters and turn them into NSStrings:

NSMutableArray *tokens = [NSMutableArray array];
for (NSUInteger i = 0; i < [string length]; ++i) {
  unichar character = [string characterAtIndex:i];
  NSString *token = [NSString stringWithFormat:@"%C", character];
  [tokens addObject:token];
}
NSLog(@"%@", tokens);

Or if you didn’t want to strip the whitespace before, you could do it in the loop:

NSMutableArray *tokens = [NSMutableArray array];
for (NSUInteger i = 0; i < [string length]; ++i) {
  unichar character = [string characterAtIndex:i];
  if ([[NSCharacterSet whitespaceCharacterSet] characterIsMember:character]) {
    continue;
  }
  NSString *token = [NSString stringWithFormat:@"%C", character];
  [tokens addObject:token];
}
NSLog(@"%@", tokens);