Question

I have a problem with NSRegularExpression. I’m sure that is my mistake, but i can’t figure it out. I have this code:

NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression         
                              regularExpressionWithPattern: nextModelName
                              options:NSRegularExpressionCaseInsensitive
                              error:&error];
[regex enumerateMatchesInString:objTmplName options:0 range:NSMakeRange(0, [objTmplName length]) usingBlock:^(NSTextCheckingResult *match, NSMatchingFlags flags, BOOL *stop){

    NSLog(@"objTmplName:%@ nextModelName:%@",objTmplName,nextModelName);
  }];

And the output is:

2012-07-30 10:59:48.779 MyApp[8470:707] objTmplName:yaoygo nextModelName:\w*
2012-07-30 10:59:48.799 MyApp[8470:707] objTmplName:yaoygo nextModelName:yo*
2012-07-30 10:59:48.808 MyApp[8470:707] objTmplName:yaoygo nextModelName:yaoygo

Why it get into when objTmplName = yaoygo and nextModelName:yo* ?

What i want to do is when my objTmplName start with “yo…” it will be true, otherway this should be false. For example:

yooygo TRUE
yaygo FALSE
yayoyoyo FALSE

Answer 1

2012-07-30 10:59:48.799 MyApp[8470:707] objTmplName:yaoygo nextModelName:yo*

Why it get into when objTmplName = yaoygo and nextModelName:yo* ?

yo* means:

y followed by any number of o (possibly none).

If you want to force at least one o, use:

yo+

After your edit to the question:

try and use the regex: ^yo.*