为什么NSUserDefaults不愿意保存我的NSDictionary？ [英] Why is NSUserDefaults unwilling to save my NSDictionary?

问题描述

我正在使用KVC序列化 NSObject 并尝试将其保存到 NSUserDefaults ，这给了我一个当我尝试存储我的 NSDictionary 时，尝试插入非属性值。

I'm using KVC to serialize an NSObject and attempt to save it to NSUserDefaults, which is giving me an Attempt to insert non-property value when I try to store my NSDictionary.

以下是相关对象的属性， MyClass ：

Following are the properties of the object in question, MyClass:

@interface MyClass : NSObject
@property (copy,nonatomic) NSNumber* value1;
@property (copy,nonatomic) NSNumber* value2;
@property (copy,nonatomic) NSString* value3;
@property (copy,nonatomic) NSString* value4;
@property (copy,nonatomic) NSString* value5;
@property (copy,nonatomic) NSString* value6;
@property (copy,nonatomic) NSString* value7;
@property (copy,nonatomic) NSString* value8;
@end

当需要保存MyClass时，它出现在：

When it is time to save MyClass it occurs here:

-(void)saveMyClass
{
  NSArray* keys = [NSArray arrayWithObjects:
                @"value1",
                @"value2",
                @"value3",
                @"value4",
                @"value5",
                @"value6",
                @"value7",
                @"value8",
                nil];
  NSDictionary* dict = [self dictionaryWithValuesForKeys:keys];
  for( id key in [dict allKeys] )
  {
    NSLog(@"%@ %@",[key class],[[dict objectForKey:key] class]);
  }
  NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
  [defaults setObject:dict forKey:[NSString stringWithString:kMyClassKey]];
  [defaults synchronize];
}

产生此输出：

2012-02-23 19:35:27.518 MyApp[10230:40b] __NSCFConstantString __NSCFNumber
2012-02-23 19:35:27.519 MyApp[10230:40b] __NSCFConstantString __NSCFNumber
2012-02-23 19:35:27.519 MyApp[10230:40b] __NSCFConstantString __NSCFString
2012-02-23 19:35:27.519 MyApp[10230:40b] __NSCFConstantString __NSCFString
2012-02-23 19:35:27.520 MyApp[10230:40b] __NSCFConstantString __NSCFString
2012-02-23 19:35:27.520 MyApp[10230:40b] __NSCFConstantString __NSCFString
2012-02-23 19:35:27.520 MyApp[10230:40b] __NSCFConstantString __NSCFString
2012-02-23 19:35:27.520 MyApp[10230:40b] __NSCFConstantString NSNull
2012-02-23 18:38:48.489 MyApp[9709:40b] *** -[NSUserDefaults setObject:forKey:]: Attempt to insert non-property value '{
    value1 = "http://www.google.com";
    value2 = "MyClassData";
    value3 = 8;
    value4 = "<null>";
    value5 = "http://www.google.com";
    value6 = 1;
    value7 = "http://www.google.com";
    value8 = 4SY8KcTSGeKuKs7s;
}' of class '__NSCFDictionary'.  Note that dictionaries and arrays in property lists must also contain only property values.`

如您所见， dict 中的所有对象都是属性列表值，其所有键都是 NSString * 。为了执行这个，我缺少什么琐事？或者我应该放弃并使用 writeToFile 或类似的？

As you can see, all of the objects in the dict are property list values and all of its keys are NSString*. What trivia am I lacking in order to execute this? Or should I give up and use writeToFile or similar?

推荐答案

道具凯文谁建议打印值，当然其中一个是 NSNull 类型，这不是属性列表值。谢谢！

Props to Kevin who suggested printing the values, of course one of which is of type NSNull which is not a property list value. Thanks!

解决我的问题的kludgy解决方案 - 使用 dictionaryWithValuesForKeys 并删除 NSNull 类型的那些。叹气

The kludgy solution to my problem - iterate over the keys of the dictionary I just produced so conveniently with dictionaryWithValuesForKeys and remove those of type NSNull. sigh

NSMutableDictionary* dict = [NSMutableDictionary dictionaryWithDictionary:[self dictionaryWithValuesForKeys:keys]];
for( id key in [dict allKeys] )
{
    if( [[dict valueForKey:key] isKindOfClass:[NSNull class]] )
    {
        // doesn't work - values that are entered will never be removed from NSUserDefaults
        //[dict removeObjectForKey:key];
        [dict setObject@"" forKey:key];
    }
}

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