how to save and read array of array in NSUserdefaults in swift?

Question

I need create an array to add objects with this format like a dictionary in Swift : ["key1": "value1", "key2": "value2"]

When I try to save it with NSUserDefaults all is correct, but when read NSUserDefaults with the key this crashes. What type of data does my var obj need?

let def = NSUserDefaults.standardUserDefaults()
var key = "keySave"
var element: AnyObject!

var array1: [AnyObject!] = []
array1.append(["key1": "val1", "key2": "val2"])
array1.append(["key1": "val1", "key2": "val2"])

//save
var savestring : [AnyObject!]
savestring = array1
var defaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(savestring, forKey: key)
defaults.synchronize()

//read
var obj: [AnyObject!] = []
if(obj != nil){
    print("size: ")
    print(obj.count) //vary long value confused..
    element = obj[0]  //crash
    print(element.objectForKey("key1"))
}

It looks like NSUserDefaults can handle String but not Array and Dictionary, working only for the NS* types describing the docs. So this looks like a bug in Swift. — zaph, Aug 10 '14 at 15:05
To go a little bit beyond what @Zaph says, I tested with [String] and it's not working, but it is working with [NSString]. Check my answer. — HpTerm, Oct 21 '14 at 12:58

Suragch · Accepted Answer · 2018-09-18T01:05:45.453

The question reads "array of array" but I think most people probably come here just wanting to know how to save an array to UserDefaults. For those people I will add a few common examples.

String array

Save array

let array = ["horse", "cow", "camel", "sheep", "goat"]

let defaults = UserDefaults.standard
defaults.set(array, forKey: "SavedStringArray")

Retrieve array

let defaults = UserDefaults.standard
let myarray = defaults.stringArray(forKey: "SavedStringArray") ?? [String]()

Int array

Save array

let array = [15, 33, 36, 723, 77, 4]

let defaults = UserDefaults.standard
defaults.set(array, forKey: "SavedIntArray")

Retrieve array

let defaults = UserDefaults.standard
let array = defaults.array(forKey: "SavedIntArray")  as? [Int] ?? [Int]()

Bool array

Save array

let array = [true, true, false, true, false]

let defaults = UserDefaults.standard
defaults.set(array, forKey: "SavedBoolArray")

Retrieve array

let defaults = UserDefaults.standard
let array = defaults.array(forKey: "SavedBoolArray")  as? [Bool] ?? [Bool]()

Date array

Save array

let array = [Date(), Date(), Date(), Date()]

let defaults = UserDefaults.standard
defaults.set(array, forKey: "SavedDateArray")

Retrieve array

let defaults = UserDefaults.standard
let array = defaults.array(forKey: "SavedDateArray")  as? [Date] ?? [Date]()

Object array

Custom objects (and consequently arrays of objects) take a little more work to save to UserDefaults. See the following links for how to do it.

Notes

The nil coalescing operator (??) allows you to return the saved array or an empty array without crashing. It means that if the object returns nil, then the value following the ?? operator will be used instead.
As you can see, the basic setup was the same for Int, Bool, and Date. I also tested it with Double. As far as I know, anything that you can save in a property list will work like this.

score 16 · Answer 2 · edited Sep 10 '18 at 19:48

Just to add on to what @Zaph says in the comments.

I have the same problem as you, as to know, the array of String is not saved. Even though Apple bridges types such as String and NSString, I wasn't able to save an array of [String] neither of [AnyObject].

However an array of [NSString] works for me.

So your code could look like that :

var key = "keySave"

var array1: [NSString] = [NSString]()
array1.append("value 1")
array1.append("value 2")

//save
var defaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(array1, forKey: key)
defaults.synchronize()

//read
if let testArray : AnyObject? = defaults.objectForKey(key) {
    var readArray : [NSString] = testArray! as [NSString]
}

Note that I created an array of NSString and not a dictionary. I didn't check if it works with a dictionary, but probably you will have to define the things as [NSString : NSString] to have it working.

EDIT

Re-reading your question and your title, you are talking of array of array. I think that as long as you stay with NSString, an array of array will work. However, if you think my answer is irrelevant, just let me know in the comments and I will remove it.

Zorayr · Answer 3 · 2015-04-16T18:38:20.923

Here is an example of reading and writing a list of objects of type SNStock that implements NSCoding - we have an accessor for the entire list, watchlist, and two methods to add and remove objects, that is addStock(stock: SNStock) and removeStock(stock: SNStock).

import Foundation

class DWWatchlistController {

  private let kNSUserDefaultsWatchlistKey: String = "dw_watchlist_key"

  private let userDefaults: NSUserDefaults

  private(set) var watchlist:[SNStock] {

    get {
      if let watchlistData : AnyObject = userDefaults.objectForKey(kNSUserDefaultsWatchlistKey) {
        if let watchlist : AnyObject = NSKeyedUnarchiver.unarchiveObjectWithData(watchlistData as! NSData) {
          return watchlist as! [SNStock]
        }
      }
      return []
    }

    set(watchlist) {
      let watchlistData = NSKeyedArchiver.archivedDataWithRootObject(watchlist)
      userDefaults.setObject(watchlistData, forKey: kNSUserDefaultsWatchlistKey)
      userDefaults.synchronize()
    }
  }

  init() {
    userDefaults = NSUserDefaults.standardUserDefaults()
  }

  func addStock(stock: SNStock) {
    var watchlist = self.watchlist
    watchlist.append(stock)
    self.watchlist = watchlist
  }

  func removeStock(stock: SNStock) {
    var watchlist = self.watchlist
    if let index = find(watchlist, stock) {
      watchlist.removeAtIndex(index)
      self.watchlist = watchlist
    }
  }

}

Remember that your object needs to implement NSCoding or else the encoding won't work. Here is what SNStock looks like:

import Foundation

class SNStock: NSObject, NSCoding
{
  let ticker: NSString
  let name: NSString

  init(ticker: NSString, name: NSString)
  {
    self.ticker = ticker
    self.name = name
  }

  //MARK: NSCoding

  required init(coder aDecoder: NSCoder) {
    self.ticker = aDecoder.decodeObjectForKey("ticker") as! NSString
    self.name = aDecoder.decodeObjectForKey("name") as! NSString
  }

  func encodeWithCoder(aCoder: NSCoder) {
    aCoder.encodeObject(ticker, forKey: "ticker")
    aCoder.encodeObject(name, forKey: "name")
  }

  //MARK: NSObjectProtocol

  override func isEqual(object: AnyObject?) -> Bool {
    if let object = object as? SNStock {
      return self.ticker == object.ticker &&
        self.name == object.name
    } else {
      return false
    }
  }

  override var hash: Int {
    return ticker.hashValue
  }
}

Hope this helps!

score 6 · Answer 4 · answered Mar 26 '18 at 09:55

Swift 4.0

Store:

let arrayFruit = ["Apple","Banana","Orange","Grapes","Watermelon"]    

 //store in user default
 UserDefaults.standard.set(arrayFruit, forKey: "arrayFruit")

Fetch:

if let arr = UserDefaults.standard.array(forKey: "arrayFruit") as? [String]{
        print(arr)
    }

score 5 · Answer 5 · edited Sep 06 '20 at 19:10

5

Here is:

var array : [String] = ["One", "Two", "Three"]
let userDefault = UserDefaults.standard
// set
userDefault.set(array, forKey: "array")
// retrieve 
if let fetchArray = userDefault.array(forKey: "array") as? [String] {
    // code 
}

edited Sep 06 '20 at 19:10

Abdul Karim

4,359
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55

answered Feb 02 '20 at 17:50

Andrei Levchenko

51
1
4

score 3 · Answer 6 · edited Oct 21 '14 at 12:46

3

Try this.

To get the data from the UserDefaults.

var defaults = NSUserDefaults.standardUserDefaults()
var dict : NSDictionary = ["key":"value"]
var array1: NSArray = dict.allValues // Create a dictionary and assign that to this array
defaults.setObject(array1, forkey : "MyKey")

var myarray : NSArray = defaults.objectForKey("MyKey") as NSArray
println(myarray)

edited Oct 21 '14 at 12:46

HpTerm

8,151
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answered Aug 07 '14 at 10:16

Alvin Varghese

842
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I add var dict: [AnyObject!] = [] and var array1: NSArray = dict but this is empty, How can make this correctly? – user3745888 Aug 07 '14 at 10:42
@AlvinVarghese Actually try the code. There is a typo and even when that is fixed the only thing saved is an array with one entry: "value". – zaph Aug 07 '14 at 11:18

score 0 · Answer 7 · answered Apr 02 '20 at 00:52

0

If you are working with Swift 5+ you have to use UserDefaults.standard.setValue(value, forKey: key) and to get saved data you have to use UserDefaults.standard.dictionary(forKey: key).

answered Apr 02 '20 at 00:52

Wimukthi Rajapaksha

961
1
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23

how to save and read array of array in NSUserdefaults in swift?

7 Answers7

String array

Int array

Bool array

Date array

Object array

Notes

Linked