Search tags in string - objective-c

Question

I have a string, and I want to search words (tags) that begin with "#" and end with "." or "," or " " I found this online, but is limited because:
- You can find a single word in the string (although there are more words)
- "RangeOfString" does not allow multiple choices
NSString *stringText = #"test #hello #world";
NSString *result = nil;
// Determine "#"
NSRange hashRange = [stringText rangeOfString:#"#" options:NSCaseInsensitiveSearch];
if (hashRange.location != NSNotFound)
{
// Determine " " location according to "#" location
NSRange endHashRange;
endHashRange.location = hashRange.length + hashRange.location;
endHashRange.length = [stringText length] - endHashRange.location;
endHashRange = [stringText rangeOfString:#" " options:NSCaseInsensitiveSearch range:endHashRange];
if (endHashRange.location != NSNotFound)
{
// Tags found: retrieve string between them
hashRange.location += hashRange.length;
hashRange.length = endHashRange.location - hashRange.location;
result = [stringText substringWithRange:hashRange];
}
}
you have idea how can I do?
Thank you!

Answer 1

You can use NSRegularExpression class, like this:
NSError *error = NULL;
NSRegularExpression *tags = [NSRegularExpression
regularExpressionWithPattern:#"[#]([^, .]+)([, .]|$)"
options:NSRegularExpressionCaseInsensitive
error:&error];
NSArray *matches = [tags matchesInString:str options:0 range:NSMakeRange(0, str.length)];
for (NSTextCheckingResult *match in matches) {
NSLog(#"%#", [str substringWithRange:[match rangeAtIndex:1]]);
}
You may need to play with your regular expression to get it just right. The reference that I liked describes the grammar of the regex language supported by Apple's classes.

Answer 2

You should use NSRegularExpression, which will give you multiple matches.
The following is an untested example:
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"\\b(#\\S*[.,])\\b" options:NSRegularExpressionCaseInsensitive];
int numberOfMatches = [regex numberOfMatchesInString:string options:0 range:NSMakeRange(0, string.length)];
NSArray *matches = [regex matchesInString:string options:0 range:NSMakeRange(0, [string length])];

Answer 3

You will most likely want to use NSScanner.
NSString *stringText = #"test #hello #world";
NSString *result = nil;
NSCharacterSet *endingChars = [NSCharacterSet characterSetWithCharactersInString:#"., "];
NSScanner *scanner = [NSScanner scannerWithString:stringText];
scanner.charactersToBeSkipped = nil;
[scanner scanUpToString:#"#" intoString:NULL];
[scanner scanString:#"#" intoString:NULL];
[scanner scanUpToCharactersFromSet:endingChars intoString:&result];
[scanner scanCharactersFromSet:endingChars intoString:NULL];
STAssertEqualObjects(result, #"hello", nil);
At that point you just loop until [scanner isAtEnd];
NSString *stringText = #"test #hello #world";
NSString *match = nil;
NSMutableArray *results = [NSMutableArray arrayWithCapacity:2];
NSCharacterSet *endingChars = [NSCharacterSet characterSetWithCharactersInString:#"., "];
NSScanner *scanner = [NSScanner scannerWithString:stringText];
scanner.charactersToBeSkipped = nil;
while (![scanner isAtEnd]) {
[scanner scanUpToString:#"#" intoString:NULL];
[scanner scanString:#"#" intoString:NULL];
[scanner scanUpToCharactersFromSet:endingChars intoString:&match];
[scanner scanCharactersFromSet:endingChars intoString:NULL];
[results addObject:match];
}
STAssertEquals(results.count, 2, nil);
STAssertEqualObjects([results objectAtIndex:0], #"hello", nil);
STAssertEqualObjects([results objectAtIndex:1], #"world", nil);