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.
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.