为什么NSUserDefaults无法在iPhone SDK中保存NSMutableDictionary？ [英] Why NSUserDefaults failed to save NSMutableDictionary in iPhone SDK?

问题描述

我想在 NSUserDefaults 中保存 NSMutableDictionary 对象。 NSMutableDictionary 中的键类型是 NSString ，值类型为 NSArray ，其中包含实现 NSCoding 的对象列表。每个文档， NSString 和 NSArray 都符合 NSCoding 。

我遇到这个错误：

[NSUserDefaults setObject：forKey： ]：尝试插入NSCFDictionary类的非属性值....

任何解决方案？

解决方案

我发现了一个替代方法，在保存之前，我对根对象（ NSArray ）使用 NSKeyedArchiver 以 NSData 结尾。然后使用UserDefaults保存 NSData 。

当我需要数据时，我读出 NSData ，并使用 NSKeyedUnarchiver 将 NSData 转换回对象。

这是一个有点麻烦，因为我需要转换/从 NSData 每次，但它只是工作。

每个请求都有一个示例：

保存：

  NSUserDefaults * defaults = [NSUserDefaults standardUserDefaults]; 
 NSMutableArray * arr = ...; // set value 
 NSData * data = [NSKeyedArchiver archivedDataWithRootObject：arr]; 
 [defaults setObject：data forKey：@theKey]; 
 [defaults synchronize]; 
  

载入：

 code> NSUserDefaults * defaults = [NSUserDefaults standardUserDefaults]; 
 NSData * data = [defaults objectForKey：@theKey]; 
 NSArray * arr = [NSKeyedUnarchiver unarchiveObjectWithData：data]; 
  

数组中的元素实现

  @interface注释项：NSObject< NSCoding> {
 NSString * value; 
} 
  

然后在执行 CommentItem 提供两种方法：

   - （void）encodeWithCoder：（NSCoder *）encoder 
 {
 [encoder encodeObject：value forKey：@Value]; 
} 
 
  - （id）initWithCoder：（NSCoder *）decoder 
 {
 self.value = [decoder decodeObjectForKey：@Value]; 
 return self; 
} 
  

任何人都有更好的解决方案？

感谢大家。

I'd like to save an NSMutableDictionary object in NSUserDefaults. The key type in NSMutableDictionary is NSString, the value type is NSArray, which contains a list of object which implements NSCoding. Per document, NSString and NSArray both are conform to NSCoding.

I am getting this error:

[NSUserDefaults setObject: forKey:]: Attempt to insert non-property value.... of class NSCFDictionary.

Any solution for this?

解决方案

I found out one alternative, before save, I encode the root object (NSArray object) using NSKeyedArchiver, which ends with NSData. Then use UserDefaults save the NSData.

When I need the data, I read out the NSData, and use NSKeyedUnarchiver to convert NSData back to the object.

It is a little cumbersome, because i need to convert to/from NSData everytime, but it just works.

Here is one example per request:

Save:

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSMutableArray *arr = ... ; // set value
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:arr];
[defaults setObject:data forKey:@"theKey"];
[defaults synchronize];

Load:

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *data = [defaults objectForKey:@"theKey"];
NSArray *arr = [NSKeyedUnarchiver unarchiveObjectWithData:data];

The element in the array implements

@interface CommentItem : NSObject<NSCoding> {
    NSString *value;
}

Then in the implementation of CommentItem, provides two methods:

-(void)encodeWithCoder:(NSCoder *)encoder
{
    [encoder encodeObject:value forKey:@"Value"];
}

-(id)initWithCoder:(NSCoder *)decoder
{
    self.value = [decoder decodeObjectForKey:@"Value"];
    return self;
}

Anyone has better solution?

Thanks everyone.

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