Swift Condensing Sentences

condensing-sentences.swift

// In reference to:
// https://www.reddit.com/r/dailyprogrammer/comments/6grwny/20170612_challenge_319_easy_condensing_sentences/

let input = """
Deep episodes of Deep Space Nine came on the television only after the news.
Digital alarm clocks scare area children.
"""

var lines = input.split(separator: "\n")

for line in lines {

    let origSentence = line.split(separator: " ")
    var sentence = origSentence.map { String($0) }
    
    func compressWords (_ first: String, _ second: String) -> String? {
        
        var output: String? = nil
        
        for i in 1...first.count {
            let range = first.index(first.endIndex, offsetBy: -i)..<first.endIndex
            let checkString = String(first[range])
            
            if second.hasPrefix(checkString) {
               output = checkString
            }
        }
        return output
    }

    for index in 0..<sentence.count - 1 {
        
        if let discard = compressWords(sentence[index], sentence[index+1]) {
            let trimmedWord = String(sentence[index+1].dropFirst(discard.count))
            sentence[index+1] = trimmedWord
        } else {
            sentence[index] = sentence[index] + " "
        }
        
    }

    print(sentence.joined(separator: ""))
    
}