Regex on NSpredicate not working as expected

Question

I'm actually totally lost trying to use a regex into a NSpredicate. What i want is a regex who find all the beginning of words in a sentence who match criteria. The fact is that doesn't work.

Here's my regex: .*\b xxx [\w-]* (where xxx is my criteria).

And here's the code

   NSString* regexString   = [NSString stringWithFormat: @".*\\b%@[\\w-]*", search];
   request.predicate       = [NSPredicate predicateWithFormat:@"adresse matches[cd] %@", regexString];

adress are a string property of my core data object. But for some obscure reason, that doesn't work. Can someone help me?

For example: CITY SANDWITCH 67200 STRASBOURG

.*\bStra[\w-]* will find STRASBOURG

but .*\b672[\w-]* or .*\bSAND[\w-]* will result nothing.

edit

I finally give up and wrote (adresse BEGINSWITH[c] %@) OR (adresse CONTAINS[c] %@) statement instead, where %@ is the search word term.

But the topic is still open if someone can explain me why simple regex formula in obj-c seems like lauching a rocket in space. What is strange is the regex actually works, but half the way it should be, like if the rule wasn't strictly followed. I'm really confused now.

Answer 1

I didn't use the same object as you did but another that I understand a bit more and that looks more like Java's one ;)

NSString* string = @"CITY SANDWITCH 67200 STRASBOURG";
NSString* search = @"SAND"; // work also with 672 or STRAS
NSString* regexString  = [NSString stringWithFormat: @".*\\b(%@[\\w]*)[\\s*\\w*]*", search];
NSError  *error  = NULL;

NSRegularExpression *regex = [NSRegularExpression
                              regularExpressionWithPattern:regexString
                              options:0
                              error:&error];

NSString *modifiedString = [regex stringByReplacingMatchesInString:string options:0 range:NSMakeRange(0, [string length]) withTemplate:@"$1"];

NSLog(@"-->%@", modifiedString);

Answer 2

Try changing regexString to

NSString* regexString   = [NSString stringWithFormat: @".*\\b%@.*", search];