Read a file one line at a time in Swift

SwiftLineReader.swift

/**

Original snipet from: https://gist.github.com/algal/23b10062a558aec7679e4c854096f88e
Forked to play around and learn sequence.

 */

import Darwin

struct LineIterator: IteratorProtocol {
    var file: UnsafeMutablePointer<FILE>
    
    init (file: UnsafeMutablePointer<FILE>) {
        self.file = file
    }
    
    mutating func next() -> String? {
        var line: UnsafeMutablePointer<CChar>?
        var linecap: Int = 0
        defer { free(line) }
        return getline(&line, &linecap, file) > 0 ? String(cString: line!) : nil
    }
}

struct LineSequence: Sequence {
    let file: UnsafeMutablePointer<FILE>
    
    func makeIterator() -> LineIterator {
        return LineIterator(file: file)
    }
}

let path = "path/to/file"
let file = fopen(path, "r")

if let filePointer = file {
    let lineSequence = LineSequence(file: filePointer)
    for line in lineSequence {
        print(line, separator: "", terminator: "")
    }
} else {
  print("Path not valid.")  
}