Swift - Reading and Writing Files(file handle)

The Swift Programming Language
Apple Inc.

開発環境

• OS X Mavericks - Apple(OS)
• Xcode 6.0 Beta 6
• Swift (プログラミング言語)

Practical Programming: An Introduction to Computer Science Using Python 3 (Pragmatic Programmers) (Paul Gries (著)、Jennifer Campbell (著)、Jason Montojo (著)、Lynn Beighley (編集)、Pragmatic Bookshelf)のChapter 10(Reading and Writing Files)、10.10(Exercises) 1.をSwiftで考えてみる。

10.10(Exercises) 1.

コード(Xcode)

main.swift

//
//  main.swift
//  sample1
//
//  Created by kamimura on 9/22/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

let name:String = input()
let s:String? = read(name)
print(s!, "\(name).out", end: "")

stdio.swift

//
//  stdio.swift
//  stdio
//
//  Created by kamimura on 8/21/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

// 標準入力(STDIN)から読み込む
func input(msg:String = "") -> String {
    print(msg)
    var in_fh = NSFileHandle.fileHandleWithStandardInput()
    var data = in_fh.availableData
    in_fh.closeFile()
    var s = NSString(data: data, encoding: NSUTF8StringEncoding)
    s = s?.substringToIndex(s!.length - 1)
    return s!
}

func read(path:String) -> String? {
    var fh = NSFileHandle(forReadingAtPath: path)
    let data = fh?.readDataToEndOfFile()
    if fh == nil {
        error("file(\(path)) can't open.")
    }
    fh?.closeFile()
    return NSString(data: data!, encoding: NSUTF8StringEncoding)
}

func print(s:String, path:String, end:String = "\n") {
    (s + end).writeToFile(path, atomically: true, encoding: NSUTF8StringEncoding, error: nil)
}

func error(msg:String) {
    let stderr = NSFileHandle.fileHandleWithStandardError()
    stderr.writeData((msg + "\n").dataUsingEncoding(NSUTF8StringEncoding)!)
    exit(1)
}

// コマンドライン引数
let argv:[String] = NSProcessInfo.processInfo().arguments.map({(x:AnyObject) -> String in x as String})

入出力結果(Console Output)

$ cat sample.txt 
sample txt
Hello, Swift!
$ ./sample1 
sample.txt
$ cat sample.txt
sample txt
Hello, Swift!
$ cat sample.txt.out 
sample txt
Hello, Swift!
$