Find duplicate Files in file system(Swift)

duplicate_files_file_system.swift

class Solution {
    func findDuplicate(_ paths: [String]) -> [[String]] {
        var map = [String:[String]]()
        
        for path in paths {
            var dir = ""
            let components = path.split(separator : " ")
            if components.count > 1 { dir = String(components[0])}
            for i in 1..<components.count {
                    if let fileNamePair = getFileNameContentPair(String(components[i])){
                        let key = fileNamePair.0
                        let value = "\(dir)/\(fileNamePair.1)"
                        if let existing =  map[key] {
                            map[key] = existing + [value]
                        }
                        else{
                            map[key] = [value]
                        }
                    }
            }
        }
        
        return map.values.filter{ $0.count > 1}
    }
    // filename(content)
    func getFileNameContentPair(_ path:String) -> (String,String)?{
        if let firstIdx = path.indexInt(of:"("), let lastIdx = path.indexInt(of:")") {
            let fileName =  String(path.prefix(firstIdx))
            let startIdx = path.index(path.startIndex, offsetBy: firstIdx - 1)
            let last = path.index(path.startIndex, offsetBy: lastIdx)
            let content = String(path[startIdx..<last])
            return (content,fileName)
        }
        return nil
    }
}

public extension String {  
  func indexInt(of char: Character) -> Int? {
    return firstIndex(of: char)?.utf16Offset(in: self)
  }
}