Swift - Read/write array of arrays to/from file

Question

Here are my files.

How can I write this array:

var listOfTasks = [["Hi", "Hello", "12:00"],["Hey there", "What's up?", "3:17"]]

to a .txt file (file.txt)? I know there are other questions about this, but they're in other languages (not Swift). I'd like for it to work on an actual iPhone. I'm happy to provide additional information if necessary. I'm new to Swift, so excuse my question if it seems too simple. NOTE: I am asking specifically about arrays containing arrays.

Thanks in advance!

Answer 1

Already answered you in your other question:

Here's a full working Playground sample:

let fileUrl = NSURL(fileURLWithPath: "/tmp/foo.plist") // Your path here
let listOfTasks = [["Hi", "Hello", "12:00"], ["Hey there", "What's up?", "3:17"]]

// Save to file
(listOfTasks as NSArray).writeToURL(fileUrl, atomically: true)

// Read from file
let savedArray = NSArray(contentsOfURL: fileUrl) as! [[String]]

print(savedArray)

Answer 2

You should use NSKeyedArchiver/NSKeyedUnarchiver to read/write your array as a property list file instead of a text file. You can save your file to the preferences folder inside the Library folder:

let preferencesDirectory =  try! NSFileManager().URLForDirectory(.LibraryDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: true).URLByAppendingPathComponent("Preferences", isDirectory: true)

let listOfTasksURL = preferencesDirectory.URLByAppendingPathComponent("listOfTasks.plist")

var listOfTasks: [[String]] {
    get {
        return NSKeyedUnarchiver.unarchiveObjectWithFile(listOfTasksURL.path!) as? [[String]] ?? []
    }
    set {
        NSKeyedArchiver.archiveRootObject(newValue, toFile: listOfTasksURL.path!)
    }
}

If you would like to test it in a playground file you will need to save it to the documents directory:

let documentsDirectory =  try! NSFileManager().URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: true)

let listOfTasksURL = documentsDirectory.URLByAppendingPathComponent("listOfTasks.plist")

var listOfTasks: [[String]] {
    get {
        return NSKeyedUnarchiver.unarchiveObjectWithFile(listOfTasksURL.path!) as? [[String]] ?? []
    }
    set {
        NSKeyedArchiver.archiveRootObject(newValue, toFile: listOfTasksURL.path!)
    }
}

listOfTasks =  [["Hi", "Hello", "12:00"],["Hey there", "What's up?", "3:17"]]

listOfTasks // [["Hi", "Hello", "12:00"], ["Hey there", "What's up?", "3:17"]]