how to alter a string with NSRegularExpression - objective-c

Question

I am a beginner in objective-c.
I have the following NSMutableString stringVal=#"[abc][test][end]";
What is the best way I should use in order to REMOVE THE LAST [] piece (e.g [end])?
I have this code:
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"\[]" options:0 error:NULL];
NSArray *matches = [regex matchesInString:stringVal options:0 range:NSMakeRange(0, [stringVal length])];
for (NSTextCheckingResult *match in matches) {
?? what should i do here?
}

Answer 1

I think you should use this regular expression pattern "\\[.*?]" then you get three matches
['[abc]', '[test]', '[end]']
then can just get the range of the third match (check that you have at least three)
NSMutableString* stringVal= [NSMutableString stringWithString:#"[abc][test][end]"];
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"\\[.*?]" options:0 error:NULL];
NSArray *matches = [regex matchesInString:stringVal options:0 range:NSMakeRange(0, [stringVal length])];
NSTextCheckingResult* match = matches[2];
NSMutableString* substring = [[stringVal substringToIndex:match.range.location] mutableCopy];

Answer 2

jbat was right that you should modify the regex. After that, all you need is the last match, so you could use
NSTextCheckingResult *match = [matches lastObject]; // Get the last match
NSRange matchRange = [match range]; // Get the position of the match segment
NSString *result = [stringVal stringByReplacingCharactersInRange:matchRange withString:#""]; // Replace the segment by an empty string.