在swift，iOS游乐场中读取文件

Question

Having searched through the many (many!) swift playground questions to even craft this code, I'm still struggling.

I've placed a text file in the Resources folder of package contents, and it appears as an alias (link) in the running temp files generated by the playground ( /var/folders/ ... ).

import UIKit

let bundle = NSBundle.mainBundle()

let myFilePath = bundle.pathForResource("dict1", ofType: "txt")

println(myFilePath)    // <-- this is correct, there is a shortcut to the Resource file at this location

var error:NSError?

var content = String(contentsOfFile:myFilePath!, encoding:NSUTF8StringEncoding, error: &error)

println(content!)  // <-- this is *NOT* the file contents [EDIT: see later note]

// Demonstrate there's no error
if let theError = error {
    print("\(theError.localizedDescription)")
} else {
    print("No error")
}

The problem being, that content is shown in the playground output as being Some "apple\\ngame\\nhow\\nswift\\ntoken" , rather than the file contents as expected.

It's finding the file, because if I change the filename, it errors. Any advice on getting the file contents?

Xcode 6.1

EDIT: So, the actual problem was that I wasn't expecting the playground output (including, println ) to be escaped. That, combined with fatigue and other stupidities led me to believe there was a problem, when none existed.

Interestingly, not everything seems to be escaped in playground:

println("foo\nbar")    // Outputs "foo\nbar", escaped
println("\\n")         // Outputs "\n", unescaped

Answer 1

You can try creating a class for opening and saving your files:

update: Xcode 10 • Swift 4.2

class File {
    class func open(_ path: String, encoding: String.Encoding = .utf8) -> String? {
        if FileManager.default.fileExists(atPath: path) {
            do {
                return try String(contentsOfFile: path, encoding: encoding)
            } catch {
                print(error)
                return nil
            }
        }
        return  nil
    }

    class func save(_ path: String, _ content: String, encoding: String.Encoding = .utf8) -> Bool {
        do {
            try content.write(toFile: path, atomically: true, encoding: encoding)
            return true
        } catch {
            print(error)
            return false
        }
    }
}

usage: File.save

let stringToSave: String = "Your text"

let didSave = File.save("\(NSHomeDirectory())/Desktop/file.txt", stringToSave) 

if didSave { print("file saved") } else { print("error saving file") } 

usage: File.open

if let loadedData = File.open("\(NSHomeDirectory())/Desktop/file.txt") {
    print(loadedData)
} else {
    println("error reading file")
 }  

If you prefer working with URL s (as I do and recommended by Apple):
_{Note that in Swift 4, the class URL already exists.}

class Url {
    class func open(url: URL) -> String? {
        do {
            return try String(contentsOf: url, encoding: String.Encoding.utf8)
        } catch {
            print(error)
            return nil
        }
    }

    class func save(url: URL, fileContent: String) -> Bool {
        do {
            try fileContent.write(to: url, atomically: true, encoding: .utf8)
            return true
        } catch {
            print(error)
            return false
        }
    }
}

Answer 2

I have seen this problem with .txt files created from .rtf files using TextEdit.

I loaded a text.txt file in the resources folder of my playground using similar code to you. The file contents was "hello there" and was made by converting an .rtf file to .txt by changing the extension.

let path = NSBundle.mainBundle().pathForResource("text", ofType: "txt")//or rtf for an rtf file
var text = String(contentsOfFile: path!, encoding: NSUTF8StringEncoding, error: nil)!
println(text)

The output was:

{\\rtf1\\ansi\\ansicpg1252\\cocoartf1343\\cocoasubrtf140 {\\fonttbl\\f0\\fswiss\\fcharset0 Helvetica;} {\\colortbl;\\red255\\green255\\blue255;} \\margl1440\\margr1440\\vieww10800\\viewh8400\\viewkind0 \\pard\\tx720\\tx1440\\tx2160\\tx2880\\tx3600\\tx4320\\tx5040\\tx5760\\tx6480\\tx7200\\tx7920\\tx8640\\pardirnatural

\\f0\\fs24 \\cf0 hello there}

So the "hello there" is embedded. This is the problem with all the layout information in a .rtf file.

I went back to TextEdit and created a true .txt file. After opening a file - Format|Make Plain Text

Now this same code gave the console output "hello there".

Hope this helps.