How to get range of specific substring even if a duplicate

Question

I want to detect the words that begin with a #, and return their specific ranges. Initially I tried using the following code:

for word in words {
    if word.hasPrefix("#") {
        let matchRange = theSentence.range(of: word)
        //Do stuff with this word
    }
}

This works fine, except if you have a duplicate hashtag it will return the range of the first occurrence of the hashtag. This is because of the nature of the range(_:) function.

Say I have the following string:

"The range of #hashtag should be different to this #hashtag"

This will return (13, 8) for both hashtags, when really it should return (13, 8) as well as (50, 8). How can this be fixed? Please note that emojis should be able to be detected in the hashtag too.

EDIT

If you want to know how to do this with emojis to, go here

You should ignore the last found # and substring beyond the last found `hastag` so it will eliminate the last position, you query should be in `while(theSentence.range(of: "#")!= nil)` — iphonic, Sep 26 '16 at 10:03
If you are going to use regular expressions then this might help: http://stackoverflow.com/a/27880748/1187415, it handles all Unicodes (Emojis, flags, ...) correctly. — Martin R, Sep 26 '16 at 10:47

score 10 · Accepted Answer · answered Sep 26 '16 at 10:19

10

Create regex for that and use it with the NSRegularExpression and find the matches range.

var str = "The range of #hashtag should be different to this #hashtag"
let regex = try NSRegularExpression(pattern: "(#[A-Za-z0-9]*)", options: [])
let matches = regex.matchesInString(str, options:[], range:NSMakeRange(0, str.characters.count))
for match in matches {
    print("match = \(match.range)")
}

answered Sep 26 '16 at 10:19

Nirav D

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Ah, I need it to work with emojis in the hashtag too – Tometoyou Sep 26 '16 at 10:31
1

@Tometoyou Let me check for that. – Nirav D Sep 26 '16 at 10:32
I guess if it could match from a hashtag up to the next space/line break it would work? – Tometoyou Sep 26 '16 at 10:50
@Tometoyou I have try for emoji but could not find solution for that, you need to ask new question with your new code that you have try might some one else will help you. – Nirav D Sep 26 '16 at 11:07
Welcome mate :) – Nirav D Sep 26 '16 at 11:19
If anyone's wondering about the answer, it can be found here: http://stackoverflow.com/questions/39701316/use-regex-to-match-emojis-as-well-as-text-in-string – Tometoyou Sep 26 '16 at 11:26
@Tometoyou The answer you have posted for this question i think it will not belongs to this one because this question is not ask with reguex with emoji, its just my thought. – Nirav D Sep 26 '16 at 12:40

score 0 · Answer 2 · answered Sep 26 '16 at 10:35

Why don't you separate your word in chunks where each chunk starts with #. Then you can know how many times your word with # appears in sentence.

Edit: I think that regex answer is the best way for this but this is an other approach for same solution.

var hastagWords = [""]
for word in words {
    if word.hasPrefix("#") {
        // Collect all words which begin with # in an array
        hastagWords.append(word)
    }
}

// Create a copy of original word since we will change it
var mutatedWord = word.copy() as! String

for hashtagWord in hastagWords {
    let range = mutatedWord.range(of: hashtagWord)

    if let aRange = range {
        // If range is OK then remove the word from original word and go to an other range
        mutatedWord = mutatedWord.replacingCharacters(in: aRange, with: "")
    }
}

How to get range of specific substring even if a duplicate

2 Answers2