Read a file one line at a time in Swift

SwiftLineReader.swift

import Darwin

/**
 Returns a lazy sequence that returns a String for every line of `file`.
 
 Example 1:
 // print all lines from a file
 let file = fopen(NSBundle.mainBundle().pathForResource("Cartfile", ofType: nil)!,"r")
 for line in lineGenerator(file) { print(line,separator: "", terminator: "") }
 fclose(file)
 
 Example 2:
 // echo lines from stdin
 for line in lineGenerator(stdin) { print(line, separator: "", terminator: "") }

 */
func lineGenerator(file:UnsafeMutablePointer<FILE>) -> AnyGenerator<String>
{
  return AnyGenerator { () -> String? in
    var line:UnsafeMutablePointer<CChar> = nil
    var linecap:Int = 0
    defer { free(line) }
    return getline(&line, &linecap, file) > 0 ? String.fromCString(line) : nil 
  }
}

let p = "/path/to/file"  // could be returned by NSBundle.pathForResource, if we were using Foundation
let f = fopen(p,"r")
let g = lineGenerator(f)
for line in g {
  // suppress print's automatic line ending, since
  // lineGenerator captures every line's own new line character.
  print(line, separator: "", terminator: "")
}

Your snippet made me learn more about Sequence and how to define a custom one.
Thanks!

Wrapped your code inside swift class in this gist