Question

我在NSUserDefults中保存一个自定义对象，该对象有多个属性，我初始化AppDelegate中自定义对象的值，我的问题是，当我尝试在viewcontroller didLoad方法中检索自定义对象属性“userToken”时，它工作，数据是正确的，但当我在视图控制器中的另一个方法中检索它时，我得到NULL注意另一个属性“uId “返回正确的值，我以相同的方式检索对象

我在这里做错了什么？非常感谢帮助

这是我如何保存和检索对象

+(void)SaveUser:(User *)user
{
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    NSData *userData = [NSKeyedArchiver archivedDataWithRootObject:user];
    [userDefaults setObject:userData forKey:@"User"];  
    [userDefaults synchronize]; 
}

+(User*)retrieveUser
{
    NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];
    NSData *userData = [ud objectForKey:@"User"];
    User *user = [NSKeyedUnarchiver unarchiveObjectWithData:userData];
    return user;    
}

这里是User对象的实现

- (id)initWithCoder:(NSCoder *)decoder 
{
   self = [super init];
   if (self)
   {    
        //uId and userToken are of type NSString
        self.uId = [decoder decodeObjectForKey:@"UID"];
        self.userToken = [decoder decodeObjectForKey:@"DeviceToken"];
   }
   return self;
}

- (void)encodeWithCoder:(NSCoder *)encoder 
{
    [encoder encodeObject:self.uId forKey:@"UID"];
    [encoder encodeObject:self.userToken forKey:@"DeviceToken"];
}

Answer 1

试试这个：另请注意，+ mean作为无法访问类属性的静态函数会使saveuser或retrieveuser函数中的所有内容都解码，而无需调用其他方法来解码它。这就是为什么你的+方法在loadview中使用它时总是会得到null值

+(void)SaveUser:(User *)user
{
    NSUserDefaults *UserDefaults = [NSUserDefaults standardUserDefaults];
    [UserDefaults setObject:[NSKeyedArchiver archivedDataWithRootObject:user] forKey:@"User"];
    [UserDefaults synchronize];
}

+(User*)retrieveUser
{
    NSUserDefaults *UserDefaults = [NSUserDefaults standardUserDefaults];
    NSData *userData = [UserDefaults objectForKey:@"User"];
    User *user = [NSKeyedUnarchiver unarchiveObjectWithData:userData];
    return user;
}

NSUserDefults返回null

1 个答案: