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

User · Answer

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!

User · Answer

Here is  var array    String      quot One quot    quot Two quot    quot Three quot   let userDefault   UserDefaults standard    set userDefault set array  forKey   quot array quot      retrieve  if let fetchArray   userDefault array forKey   quot array quot   as   String           code

User · Answer

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    Save custom objects into NSUserDefaults Docs for saving color to UserDefaults  Attempt to set a non-property-list object as an NSUserDefaults   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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

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

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