NSCoder沒有正確返回值

在下面的代碼中，屬性從未在sharedInstance方法中正確設置，我找不到原因。看起來我有正確的價值，但在我將它與存檔器一起保存之前。NSCoder沒有正確返回值

#import "User.h" 

    static User *sharedInstance = nil; 

    #define NAME @"name" 
    #define USER_ID @"id" 
    #define ACCOUNT_ID @"account_id" 
    #define USER_NAME @"username" 
    #define ADMIN @"admin" 
    #define CURRENT_USER @"current_user" 

    @implementation KSUser 

    + (id)sharedInstance 
    { 
     @synchronized(self) { 
      if (sharedInstance == nil) { 
       NSData *userData = [[NSUserDefaults standardUserDefaults] objectForKey:CURRENT_USER]; 
       if (userData) { 
        sharedInstance = [NSKeyedUnarchiver unarchiveObjectWithData:userData]; 
       } 
       else { 
        sharedInstance = [[super alloc] init]; 
       } 
      } 
     } 
     return sharedInstance; 
    } 

    - (void)populateFromJSON:(NSDictionary *)json 
    { 
     sharedInstance.name = json[NAME]; 
     sharedInstance.accountId = json[ACCOUNT_ID]; 
     sharedInstance.userId = json[USER_ID]; 
     sharedInstance.userName = json[USER_NAME]; 
     sharedInstance.admin = [json[ADMIN] boolValue]; 
     sharedInstance.loggedIn = YES; 
     NSLog(@"values are: name: %@, %@, %@, %@", sharedInstance.name, sharedInstance.accountId, sharedInstance.userId, sharedInstance.userName); 
    } 

    - (void)logout 
    { 
     sharedInstance.name = nil; 
     sharedInstance.accountId = nil; 
     sharedInstance.userId = nil; 
     sharedInstance.userName = nil; 
     sharedInstance.admin = NO; 
     sharedInstance.loggedIn = NO; 
     [self saveState]; 

    } 

    - (void)saveState 
    { 
     NSLog(@"values are: name: %@, %@, %@, %@", sharedInstance.name, sharedInstance.accountId, sharedInstance.userId, sharedInstance.userName); 
     NSData *data = [NSKeyedArchiver archivedDataWithRootObject:sharedInstance]; 
     [[NSUserDefaults standardUserDefaults] setObject:data forKey:CURRENT_USER]; 
    } 

    - (void)encodeWithCoder:(NSCoder *)aCoder 
    { 
     [aCoder encodeObject:sharedInstance.userId forKey:USER_ID]; 
     [aCoder encodeObject:sharedInstance.accountId forKey:ACCOUNT_ID]; 
     [aCoder encodeObject:sharedInstance.name forKey:NAME]; 
     [aCoder encodeObject:sharedInstance.userName forKey:USER_NAME]; 
     [aCoder encodeBool:sharedInstance.admin forKey:ADMIN]; 
    } 

    - (id)initWithCoder:(NSCoder *)aDecoder 
    { 
     if (self = [super init]) { 
      sharedInstance.userId = [aDecoder decodeObjectForKey:USER_ID]; 
      sharedInstance.accountId = [aDecoder decodeObjectForKey:ACCOUNT_ID]; 
      sharedInstance.name = [aDecoder decodeObjectForKey:NAME]; 
      sharedInstance.userName = [aDecoder decodeObjectForKey:USER_NAME]; 
      sharedInstance.admin = [aDecoder decodeBoolForKey:ADMIN]; 
     } 
     return self; 
    } 

    @end

任何幫助將不勝感激。

來源

2013-03-21 Cocoa Nub

這是因爲在你的方法全局變量sharedinstance - （ID）的initWithCoder：（NSCoder *）aDecoder始終是零

來源

2013-03-21 17:03:09

你是對的，但實際上，當我檢查出來的的initWithCoder解碼器的值，我得到這個： PO [解碼器decodeObjectForKey：@「user_ID的」] （ID）1 $ = 00000000 – 2013-03-21 17:12:09

這是因爲你沒有這樣的key @「user_id」。 – 2013-03-21 17:16:15

鑰匙存在。 – 2013-03-21 17:19:48

在initWithCoder:不涉及共享實例，而是改爲self。在執行時sharedInstance爲零。

此外，您只能在註銷後調用saveState，因此它只保存零值。

來源

2013-03-21 17:16:20

感謝您的反饋。上面的人指出關於sharedInstance。我實際上調用另一個類的saveState方法，所以我認爲它是持久的值。 – 2013-03-21 17:20:14

NSCoder沒有正確返回值

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