NSUserDefaults：返回整数，不返回NSArray

Question

I'm trying to store both an integer and NSArray with the NSUserDefaults, but I only can correctly retrieve the integer. When I try to recover the NSArray, it returns an empty array.

I start with a custom class XMLParser.m.

//XMLParser.m

//NSArray 'stored' correctly contains 10 data objects. 'stored' is an NSArray property of the XMLParser class
numberOfEvents = [stored count];
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:stored forKey:@"eventsList"];
[defaults setInteger:numberOfEvents forKey:@"numberOfEvents"];
[defaults synchronize];

But when I try to access the data in another class, ie. my AppDelegate, I get an empty NSArray

//myApplicationAppDelegate.m
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
int value = [defaults integerForKey:@"numberOfEvents"];  //returns 10
parsedEventsList = [defaults arrayForKey:@"eventsList"];  //parsedEventsList is an NSArray property of myApplicationAppDelegate class
int value2 = [parsedEventsList count]; //***returns 0***

I've even tried using

[defaults objectForKey:@"eventsList"]

and it's still returning nothing.

Thoughts? Thanks!

Answer 1

您stored数组中的所有对象都必须是属性列表对象（即NSData，NSDate，NSNumber，NSString，NSArray或NSDictionary的实例）。

Answer 2

Your problem appears to be that your objects are all custom. I think you may have forgotten to make them serializable if you add code similar to this (for each of your objects) then it should work

- (void)encodeWithCoder:(NSCoder *)encoder {

   //Encode properties, other class variables, etc
   [encoder encodeObject:self.obj1 forKey:@"obj1"];
   [encoder encodeObject:self.obj2 forKey:@"obj2"];
}

- (id)initWithCoder:(NSCoder *)decoder {
   if((self = [super init])) {
       //decode properties, other class vars
       self.obj1 = [decoder decodeObjectForKey:@"obj1"];
       self.obj2 = [decoder decodeObjectForKey:@"obj2"];
   }
return self;
}