cuoong/SplitTweet

SplitTweet

SplitTweet allow users to post short message limited to 50 characters.

Enviroment

• iOS 13.0
• Xcode 11
• Swift 5.1

What I've done

• Logic for split message tweet
• TweetSplit application
• Unit test

Steps to SplitTweet works

• Declare TWEET_MAX_LENGTH variable, so we can easy to change it later

private let TWEET_MAX_LENGTH = 50

• Step 1: Standard input tweet.

extension String { 
    public func standardizedWhitespace() -> String {
        let components = self.components(separatedBy: .whitespacesAndNewlines)
        return components.filter { !$0.isEmpty }.joined(separator: " ")
    }
}

• Step 2: Check a tweet is empty

if tweetString.count == 0 {
  return []
}

• Step 3: Check a tweet has number of characters smaller or equal 50. Return message.

if tweetString.count <= TWEET_MAX_LENGTH {
   return([tweetString])
}

• Step 4: Check if a tweet contains a word which has more than 50 characters.

let parts = tweetString.components(separatedBy:" ")
//Check string more than 50 chracters
for item in parts {
    if item.count > TWEET_MAX_LENGTH {
       return []
    }
}

• Step 5: Implement SplitTweet logic

Dividing the assuming number of subtweets to different ranges. (1-9, 10-99, 100-999...) Why should we do that? For example, if the number of subtweets is from 1-9, all the indicator is in form of "x/x " which needs 4 characters to present. If the number of subtweets if from 10-99, the indicators are in form of "x/yy "(5 characters) or "xx/yy " (6 characters).

var maxNumberSubTweet = 1
var count = 0
while true {
      let result = combineMessages(parts, withMaxNumberSubTweet: maxNumberSubTweet, AndMaximumTweetLength: TWEET_MAX_LENGTH)
      if result.success {
         return result.subTweets
      } else {
        count = count + 1
        maxNumberSubTweet = Int(powf(10.0, Float(count))) - 1;
      }
}

We will run into many ranges until we find the suitable results. In each range,

• Create a new sentence with a first word in the tweet.
• We will loop all words in a tweet
  • Calculate the index of the subtweet.

  var numberSubTweet = 1

  • Calculate the number of characters that the indicators need.

  var maxSubTweetLength = maxTweetLength - lengthOfIndicator(numberSubTweet, andMaxNumberOfSubTweet: maxNumberSubTweet)

  • Try to append a word into a sentence if there is a space. If not, create a new subtweet and append a proccessing word to subtweet.

  for index in 1..<(messages.count) {
      let message  = messages[index]
  
      if (sentence.count + message.count + 1) <= maxSubTweetLength {
          sentence = "\(sentence) \(message)"
      } else {
          results.append(sentence)
          numberSubTweet = numberSubTweet + 1
          maxSubTweetLength = maxTweetLength - lengthOfIndicator(numberSubTweet, andMaxNumberOfSubTweet: maxNumberSubTweet)
          sentence = message
      }
  
      if numberSubTweet > maxNumberSubTweet {
          return Result(subTweets: [], success: false)
      }
  }

  • If the number of subtweets is out of the defined range, we will try to increase the assuming number of subtweets to the next range.

    if numberSubTweet > maxNumberSubTweet {
        return Result(subTweets: [], success: false)
    }

• Loop to all subtweets, append the indicator and return the result.

  for (i, sentence) in results.enumerated() {
     results[i] = "\(i+1)/\(numberSubTweet) \(sentence)"
  }
  return Result(subTweets:results, success: true)

License

SplitTweet is released under the MIT license. See LICENSE for details.