How can I read a file in a swift playground

Question

Im trying to read a text file using a Swift playground with the following

let dirs : String[]? =    NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory         


        

Answer 1

String.stringWithContentsOfFile is DEPRECATED and doesn't work anymore with Xcode 6.1.1

Create your documentDirectoryUrl

let documentDirectoryUrl = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first! as NSURL

To make sure the file is located there you can use the finder command Go To Folder e copy paste the printed documentDirectoryUrl.path there

println(documentDirectoryUrl.path!)
// should look like this: /Users/userName/Library/Containers/com.apple.dt.playground.stub.OSX.PLAYGROUNDFILENAME-5AF5B25D-D0D1-4B51-A297-00015EE97F13/Data/Documents

Just append the file name to the folder url as a path component

let fileNameUrl = documentDirectoryUrl.URLByAppendingPathComponent("ReadMe.txt")
var fileOpenError:NSError?

Check if the file exists before attempting to open it

if NSFileManager.defaultManager().fileExistsAtPath(fileNameUrl.path!) {

    if let fileContent = String(contentsOfURL: fileNameUrl, encoding: NSUTF8StringEncoding, error: &fileOpenError) {
        println(fileContent)        // prints ReadMe.txt contents if successful
    } else {
        if let fileOpenError = fileOpenError {
            println(fileOpenError)  // Error Domain=NSCocoaErrorDomain Code=XXX "The file “ReadMe.txt” couldn’t be opened because...."
        }
    }
} else {
    println("file not found")
}

Answer 2

You can also put your file into your playground's resources. To do this: show Project Navigator with CMD + 1. Drag and drop your file into the resources folder. Then read the file:

On XCode 6.4 and Swift 1.2:

var error: NSError?
let fileURL = NSBundle.mainBundle().URLForResource("Input", withExtension: "txt")
let content = String(contentsOfURL: fileURL!, encoding: NSUTF8StringEncoding, error: &error)

On XCode 7 and Swift 2:

let fileURL = NSBundle.mainBundle().URLForResource("Input", withExtension: "txt")
let content = try String(contentsOfURL: fileURL!, encoding: NSUTF8StringEncoding)

On XCode 8 and Swift 3:

let fileURL = Bundle.main.url(forResource: "Input", withExtension: "txt")
let content = try String(contentsOf: fileURL!, encoding: String.Encoding.utf8)

If the file has binary data, you can use NSData(contentsOfURL: fileURL!) or Data(contentsOf: fileURL!) (for Swift 3).

Answer 3

This works for me. The only thing I changed was to be explicit about the file name (which is implied in your example) - perhaps you have a typo in the off-screen definition of the "file" variable?

let dirs = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true) as? [String]

let file = "trial.txt" // My change to your code - yours is presumably set off-screen
if let directories = dirs {
  let dir = directories[0]; //documents directory
  let path = dir.stringByAppendingPathComponent(file);

  //read
  let content = NSString(contentsOfFile: path, usedEncoding: nil, error: nil)
  // works...
}

Update Swift 4.2

As @raistlin points out, this would now be

let dirs = NSSearchPathForDirectoriesInDomains(
              FileManager.SearchPathDirectory.documentDirectory,
              FileManager.SearchPathDomainMask.userDomainMask,
              true)

or, more tersely:

let dirs = NSSearchPathForDirectoriesInDomains(.documentDirectory,
                                .userDomainMask, true)

Answer 4

On Mavericks with Xcode 6.0.1 you can read using iOS platform too.

import UIKit
let dirs : [String]? =    NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true) as? [String]
let myDir = "/Shared Playground Data"

let file = "README.md" // My change to your code - yours is presumably set off-screen
if (dirs != nil) {
  let directories:[String] = dirs!;
  let dir = directories[0] + myDir; // iOS playground documents directory
  let path = dir.stringByAppendingPathComponent(file);

  //read
  let content = String.stringWithContentsOfFile(path, encoding: NSUTF8StringEncoding, error: nil)
  // works...
  println(content!)
}

Remember, you need to create a directory called "Shared Playground Data" in your Documents directory. Im my case I used this command: mkdir "/Users/joao_parana/Documents/Shared Playground Data" and put there my file README.md

Answer 5

I was unable to read a file with ease in playground and ended up just creating a command line app in Xcode. This seemed to work for me very well.

Answer 6

While the answer has been supplied for a quick fix, there is a better solution.

Each time the playground is opened it will be assigned a new container. This means using the normal directory structure you would have to copy the file you want into the new container every time.

Instead, inside the container there is a symbolic link to a Shared Playground Data directory (/Users/UserName/Documents/Shared Playground Data) which remains when reopening the playground, and can be accessed from multiple playgrounds.

You can use XCPlayground to access this shared folder.

import XCPlayground

let path = XCPlaygroundSharedDataDirectoryURL.appendingPathComponent("foo.txt")

The official documentation can be found here: XCPlayground Module Reference

Cool post on how to organize this directory per-playground: Swift, Playgrounds, and XCPlayground

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UPDATE: For swift 4.2 use playgroundSharedDataDirectory. Don't need to import anything. Looks like:

let path = playgroundSharedDataDirectory.appendingPathComponent("file")