How can I read a file in a swift playground - swift

Question

Im trying to read a text file using a Swift playground with the following
let dirs : String[]? = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true) as? String[]
if (dirs != nil) {
let directories:String[] = dirs!;
let dir = directories[0]; //documents directory
let path = dir.stringByAppendingPathComponent(file);
//read
let content = String.stringWithContentsOfFile(path, encoding: NSUTF8StringEncoding, error: nil)
}
However this fails with no error. It seems the first line stops the playground from outputting anything below

Answer 1

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 2

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
UPDATE: For swift 4.2 use playgroundSharedDataDirectory. Don't need to import anything.
Looks like:
let path = playgroundSharedDataDirectory.appendingPathComponent("file")

Answer 3

1. Access a file that is located in the Resources folder of your Playground
With Swift 3, Bundle has a method called url(forResource:withExtension:). url(forResource:withExtension:) has the following declaration:
func url(forResource name: String?, withExtension ext: String?) -> URL?
Returns the file URL for the resource identified by the specified name and file extension.
You can use url(forResource:withExtension:) in order to read the content of a json file located in the Resources folder of an iOS or Mac Playground:
import Foundation
do {
guard let fileUrl = Bundle.main.url(forResource: "Data", withExtension: "json") else { fatalError() }
let data = try Data(contentsOf: fileUrl)
let json = try JSONSerialization.jsonObject(with: data, options: [])
print(json)
} catch {
print(error)
}
You can use url(forResource:withExtension:) in order to read the content of a text file located in the Resources folder of an iOS or Mac Playground:
import Foundation
do {
guard let fileUrl = Bundle.main.url(forResource: "Text", withExtension: "txt") else { fatalError() }
let text = try String(contentsOf: fileUrl, encoding: String.Encoding.utf8)
print(text)
} catch {
print(error)
}
As an alternative to let image = UIImage(named: "image"), you can use url(forResource:withExtension:) in order to access an image located in the Resources folder of an iOS Playground:
import UIKit
do {
guard let fileUrl = Bundle.main.url(forResource: "Image", withExtension: "png") else { fatalError() }
let data = try Data(contentsOf: fileUrl)
let image = UIImage(data: data)
} catch {
print(error)
}
2. Access a file that is located in the ~/Documents/Shared Playground Data folder of your computer
With Swift 3, PlaygroundSupport module provides a global constant called playgroundSharedDataDirectory. playgroundSharedDataDirectory has the following declaration:
let playgroundSharedDataDirectory: URL
The path to the directory containing data shared between all playgrounds.
You can use playgroundSharedDataDirectory in order to read the content of a json file located in the ~/Documents/Shared Playground Data folder of your computer from an iOS or Mac Playground:
import Foundation
import PlaygroundSupport
do {
let fileUrl = PlaygroundSupport.playgroundSharedDataDirectory.appendingPathComponent("Data.json")
let data = try Data(contentsOf: fileUrl)
let json = try JSONSerialization.jsonObject(with: data, options: [])
print(json)
} catch {
print(error)
}
You can use playgroundSharedDataDirectory in order to read the content of a text file located in the ~/Documents/Shared Playground Data folder of your computer from an iOS or Mac Playground:
import Foundation
import PlaygroundSupport
do {
let fileUrl = PlaygroundSupport.playgroundSharedDataDirectory.appendingPathComponent("Text.txt")
let text = try String(contentsOf: fileUrl, encoding: String.Encoding.utf8)
print(text)
} catch {
print(error)
}
You can use playgroundSharedDataDirectory in order to access an image located in the ~/Documents/Shared Playground Data folder of your computer from an iOS Playground:
import UIKit
import PlaygroundSupport
do {
let fileUrl = PlaygroundSupport.playgroundSharedDataDirectory.appendingPathComponent("Image.png")
let data = try Data(contentsOf: fileUrl)
let image = UIImage(data: data)
} catch {
print(error)
}

Answer 4

Swift 3 (Xcode 8)
The code below works in both iOS and macOS playgrounds. The text file ("MyText.txt" in this example) must be in the Resources directory of the playground. (Note: You may need to open the navigator window to see the directory structure of your playground.)
import Foundation
if let fileURL = Bundle.main.url(forResource:"MyText", withExtension: "txt")
{
do {
let contents = try String(contentsOf: fileURL, encoding: String.Encoding.utf8)
print(contents)
} catch {
print("Error: \(error.localizedDescription)")
}
} else {
print("No such file URL.")
}

Answer 5

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 6

Select the .playground file.
Open Utility inspector, In the playground press opt-cmd-1 to open the File Inspector. You should see the playground on the right. If you don't have it selected, press cmd-1 to open the Project Navigator and click on the playground file.
Under 'Resource Path' in Playground Settings choose 'Relative To Playground' and platform as OSX.

Answer 7

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 8

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 9

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 10

The other answers, relying on "playgroundSharedDataDirectory" never works for me, especially if using an iOS playground.
let documentsDirectoryShareURL = PlaygroundSupport.playgroundSharedDataDirectory.absoluteURL
let fileManager = FileManager()
try? fileManager.copyItem(at: URL(fileURLWithPath: "/Users/rufus/Documents/Shared Playground Data/"), to: documentsDirectoryShareURL)
I just do the above now. I can populate my documents/shared folder, and it is just manually automatically copied to the playgrounds documents directory.
My code will not overwrite files that exist there. You could enhance this if you need it to look at file timestamps and then copy if necessary etc.

Answer 11

Swift 5.7.1 - Xcode 14.1
func readFile() -> [String] {
if let fileURL = Bundle.main.url(forResource: "File", withExtension: "txt") {
do {
let content = try String(contentsOf: fileURL)
var x = content.components(separatedBy: "\n")
x.removeAll { data in
data.isEmpty
}
return x
} catch {
print(error)
}
}
return [String]()
}
//Usage:
let input = readFile()