Question

I don’t know how I should do this, I have tried using code like:

NSString *stringToFind = @"Hi";
NSString *fullString = @"Hi Objective C!";
NSRange range = [fullString rangeOfString :stringToFind];
if (range.location != NSNotFound)
{
    NSLog(@"I found something.");
}

But it doesn’t fit my needs, I want to search for a string like #customstring (# means a tag) where the tag is specified by the user so they enter something like this Something #hello #world, what I want to do is search for all the # and the string attached to it and save it somewhere.

EDIT: The tag string created, I am saving that in a plist, but when I save it, it only saves one tag because I simply specified the string as tag. So like this:

[db addNewItem:label tagString:tag];

I need all of the tags created. For example in my logs:

I log tag, this comes up #tag,
I log tag again with two tags like this Something #hello #world I get two tags like this:#hello & #world each separate logs.

The result I want is this:

#hello, #world and then store it in a string and save it to my DB.

Answer 1

You should use a regular expression:

NSString *input = @"Something #hello #world";

NSRegularExpression *regex = [[NSRegularExpression alloc] initWithPattern:@"#\\w+" options:0 error:nil];
NSArray *matches = [regex matchesInString:input options:0 range:NSMakeRange(0, input.length)];

NSLog(@"%d matches found.", matches.count);
for (NSTextCheckingResult *match in matches) {
    NSString *tag = [input substringWithRange:[match range]];
    NSLog(@"%@", tag);
}
// #hello
// #world

---

EDIT To get the tags without the hash character #, you should use a capturing group in the regex like the following:

NSString *input = @"Something #hello #world";

NSRegularExpression *regex = [[NSRegularExpression alloc] initWithPattern:@"#(\\w+)" options:0 error:nil];
NSArray *matches = [regex matchesInString:input options:0 range:NSMakeRange(0, input.length)];

NSLog(@"%d matches found.", matches.count);
for (NSTextCheckingResult *match in matches) {
    NSString *tag = [input substringWithRange:[match rangeAtIndex:1]];
    NSLog(@"%@", tag);
}
// hello
// world

---

EDIT To get a string that contains the input string except the tags, you can use the following method:

NSString *stringWithoutTags = [regex stringByReplacingMatchesInString:input options:0 range:NSMakeRange(0, input.length) withTemplate:@""];
NSLog(@"%@", stringWithoutTags);
// Something

---

Edit Now that you have the different tags, you can create a string that contains them like this:

NSMutableArray *tagsArray = [NSMutableArray array];
for (NSTextCheckingResult *match in matches) {
    NSString *tag = [input substringWithRange:[match range]];
    [tagsArray addObject:tag];
}
NSString *tagsString = [tagsArray componentsJoinedByString:@", "];
NSLog(@"tagsString: %@", tagsString);