How to store custom objects in NSUserDefaults

Question

Alright  so I ve been doing some poking around  and I realize my problem  but I don t know how to fix it   I have made a custom class to hold some data   I make objects for this class  and I need to them to last between sessions   Before I was putting all my information in NSUserDefaults  but this isn t working   - NSUserDefaults setObject forKey    Attempt to insert non-property value   lt Player  0x3b0cc90 gt   of class  Player     That is the error message I get when I put my custom class   Player   in the NSUserDefaults   Now  I ve read up that apparently NSUserDefaults only stores some types of information   So how an I get my objects into NSUSerDefaults   I read that there should be a way to to  encode  my custom object and then put it in  but I m not sure how to implement it  help would be appreciated   Thank you       EDIT      Alright  so I worked with the code given below  Thank you    but I m still having some issues   Basically  the code crashes now and I m not sure why  because it doesn t give any errors   Perhaps I m missing something basic and I m just too tired  but we ll see   Here is the implementation of my Custom class   Player     interface Player   NSObject       NSString  name      NSNumber  life        Log of player s life     Getting functions  return the info -  NSString   name  -  int life    -  id init     These are the setters -  void setName  NSString   input    string -  void setLife  NSNumber   input    number       end   Implementation File    import  Player h   implementation Player -  id init       if  self    super init              self setName   Player Name             self setLife  NSNumber numberWithInt 20             self setPsnCounters  NSNumber numberWithInt 0              return self     -  NSString   name  return name   -  int life  return  life intValue    -  void setName  NSString   input        input retain       if  name    nil             name release             name   input    -  void setLife  NSNumber   input        input retain       if  life    nil             life release             life   input       This code has been added to support encoding and decoding my objecst     - void encodeWithCoder  NSCoder   encoder         Encode the properties of the object      encoder encodeObject self name forKey   name         encoder encodeObject self life forKey   life       - id initWithCoder  NSCoder   decoder       self    super init       if   self    nil                   decode the properties         self name    decoder decodeObjectForKey   name            self life    decoder decodeObjectForKey   life              return self    - void dealloc        name release        life release        super dealloc      end   So that s my class  pretty straight forward  I know it works in making my objects   So here is the relevant parts of the AppDelegate file  where I call the encryption and decrypt functions     class MainViewController    interface MagicApp201AppDelegate   NSObject  lt UIApplicationDelegate gt        UIWindow  window      MainViewController  mainViewController      property  nonatomic  retain  IBOutlet UIWindow  window   property  nonatomic  retain  MainViewController  mainViewController   - void saveCustomObject  Player   obj  - Player   loadCustomObjectWithKey  NSString  key     end   And then the important parts of the implementation file        import  MagicApp201AppDelegate h       import  MainViewController h       import  Player h        implementation MagicApp201AppDelegate        synthesize window       synthesize mainViewController        -  void applicationDidFinishLaunching  UIApplication   application       NSUserDefaults  prefs    NSUserDefaults standardUserDefaults             First check to see if some things exist         int startup    prefs integerForKey   appHasLaunched            if  startup    nil      Make the single player          Player  singlePlayer     Player alloc  init           NSLog   NSString alloc  initWithFormat      n d n d   singlePlayer name    singlePlayer life    singlePlayer psnCounters         test           Encode the single player so it can be stored in UserDefaults         id test    MagicApp201AppDelegate new            test saveCustomObject singlePlayer            test release      prefs synchronize      - void saveCustomObject  Player   object        NSUserDefaults  prefs    NSUserDefaults standardUserDefaults       NSData  myEncodedObject    NSKeyedArchiver archivedDataWithRootObject object        prefs setObject myEncodedObject forKey   testing       - Player   loadCustomObjectWithKey  NSString  key       NSUserDefaults  prefs    NSUserDefaults standardUserDefaults       NSData  myEncodedObject    prefs objectForKey key        Player  obj    Player    NSKeyedUnarchiver unarchiveObjectWithData  myEncodedObject       return obj      Eeee  sorry about all the code   Just trying to help   Basically  the app will launch and then crash immediatly   I ve narrowed it down to the encryption part of the app  that s where it crashes  so I m doing something wrong but I m not sure what   Help would be appreciated again  thank you    I haven t gotten around to decrypting yet  as I haven t gotten encrypting working yet

User · Answer

I create a library RMMapper  https   github com roomorama RMMapper  to help save custom object into NSUserDefaults easier and more convenient  because implementing encodeWithCoder and initWithCoder is super boring   To mark a class as archivable  just use   import  NSObject RMArchivable h   To save a custom object into NSUserDefaults    import  NSUserDefaults RMSaveCustomObject h  NSUserDefaults  defaults    NSUserDefaults standardUserDefaults    defaults rm setCustomObject user forKey   SAVED DATA      To get custom obj from NSUserDefaults   user    defaults rm customObjectForKey   SAVED DATA

User · Answer

Synchronize the data object that you have saved into NSUserDefaults   - void saveCustomObject  Player   object        NSUserDefaults  prefs    NSUserDefaults standardUserDefaults       NSData  myEncodedObject    NSKeyedArchiver archivedDataWithRootObject object        prefs setObject myEncodedObject forKey   testing         prefs synchronize       Hope this will help you  Thanks

User · Answer

Taking  chrissr s answer and running with it  this code can be implemented into a nice category on NSUserDefaults to save and retrieve custom objects    interface NSUserDefaults  NSUserDefaultsExtensions   -  void saveCustomObject  id lt NSCoding gt  object                      key  NSString   key  -  id lt NSCoding gt  loadCustomObjectWithKey  NSString   key    end    implementation NSUserDefaults  NSUserDefaultsExtensions    -  void saveCustomObject  id lt NSCoding gt  object                      key  NSString   key       NSData  encodedObject    NSKeyedArchiver archivedDataWithRootObject object        self setObject encodedObject forKey key        self synchronize       -  id lt NSCoding gt  loadCustomObjectWithKey  NSString   key       NSData  encodedObject    self objectForKey key       id lt NSCoding gt  object    NSKeyedUnarchiver unarchiveObjectWithData encodedObject       return object      end   Usage     NSUserDefaults standardUserDefaults  saveCustomObject myObject key   myKey

User · Answer

On your Player class  implement the following two methods  substituting calls to encodeObject with something relevant to your own object    -  void encodeWithCoder  NSCoder   encoder         Encode properties  other class variables  etc      encoder encodeObject self question forKey   question         encoder encodeObject self categoryName forKey   category         encoder encodeObject self subCategoryName forKey   subcategory       -  id initWithCoder  NSCoder   decoder       if  self    super init                decode properties  other class vars         self question    decoder decodeObjectForKey   question            self categoryName    decoder decodeObjectForKey   category            self subCategoryName    decoder decodeObjectForKey   subcategory              return self      Reading and writing from NSUserDefaults   -  void saveCustomObject  MyObject   object key  NSString   key       NSData  encodedObject    NSKeyedArchiver archivedDataWithRootObject object       NSUserDefaults  defaults    NSUserDefaults standardUserDefaults        defaults setObject encodedObject forKey key        defaults synchronize       -  MyObject   loadCustomObjectWithKey  NSString   key       NSUserDefaults  defaults    NSUserDefaults standardUserDefaults       NSData  encodedObject    defaults objectForKey key       MyObject  object    NSKeyedUnarchiver unarchiveObjectWithData encodedObject       return object      Code shamelessly borrowed from  saving class in nsuserdefaults

User · Answer

Swift 4 introduced the Codable protocol which does all the magic for these kinds of tasks  Just conform your custom struct class to it  struct Player  Codable     let name  String   let life  Double    And for storing in the Defaults you can use the PropertyListEncoder Decoder  let player   Player name   quot Jim quot   life  3 14  UserDefaults standard set try  PropertyListEncoder   encode player   forKey  kPlayerDefaultsKey   let storedObject  Data   UserDefaults standard object forKey  kPlayerDefaultsKey  as  Data let storedPlayer  Player   try  PropertyListDecoder   decode Player self  from  storedObject   It will work like that for arrays and other container classes of such objects too  try  PropertyListDecoder   decode  Player  self  from  storedArray

User · Answer

If anybody is looking for a swift version   1  Create a custom class for your data  class customData  NSObject  NSCoding   let name   String let url   String let desc   String  init tuple    String String String        self name   tuple 0     self url   tuple 1     self desc   tuple 2   func getName   - gt  String       return name   func getURL   - gt  String      return url   func getDescription   - gt  String       return desc   func getTuple   - gt   String String String        return  self name self url self desc     required init coder aDecoder  NSCoder        self name   aDecoder decodeObjectForKey  name   as  String     self url   aDecoder decodeObjectForKey  url   as  String     self desc   aDecoder decodeObjectForKey  desc   as  String    func encodeWithCoder aCoder  NSCoder        aCoder encodeObject self name  forKey   name       aCoder encodeObject self url  forKey   url       aCoder encodeObject self desc  forKey   desc          2  To save data use following function   func saveData                 let data    NSKeyedArchiver archivedDataWithRootObject custom          let defaults   NSUserDefaults standardUserDefaults           defaults setObject data  forKey  customArray            3  To retrieve   if let data   NSUserDefaults standardUserDefaults   objectForKey  customArray   as  NSData                        custom   NSKeyedUnarchiver unarchiveObjectWithData data  as   customData              Note  Here I am saving and retrieving an array of the custom class objects

User · Answer

Swift 3  class MyObject  NSObject  NSCoding        let name   String     let url   String     let desc   String      init tuple    String String String            self name   tuple 0         self url   tuple 1         self desc   tuple 2           func getName   - gt  String           return name           func getURL   - gt  String          return url           func getDescription   - gt  String           return desc           func getTuple   - gt   String  String  String            return  self name self url self desc             required init coder aDecoder  NSCoder            self name   aDecoder decodeObject forKey   name   as  String               self url   aDecoder decodeObject forKey   url   as  String               self desc   aDecoder decodeObject forKey   desc   as  String                  func encode with aCoder  NSCoder            aCoder encode self name  forKey   name           aCoder encode self url  forKey   url           aCoder encode self desc  forKey   desc                 to store and retrieve   func save                 let data    NSKeyedArchiver archivedData withRootObject  object              UserDefaults standard set data  forKey  customData                      func get   - gt  MyObject                guard let data   UserDefaults standard object forKey   customData   as  Data else   return nil               return NSKeyedUnarchiver unarchiveObject with  data  as  MyObject

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