Encode NSMutableArray partially with NSKeyedArchiver

Question

I have my Person class which implements NSCoding protocol:

@interface Person : NSObject <NSCoding>
@property NSString *name;
@property float salary;
@end

@implementation Person
-(void)encodeWithCoder:(NSCoder *)aCoder
{

    [aCoder encodeObject:_name forKey:@"name"];
    [aCoder encodeFloat:_salary forKey:@"salary"];
}

-(id)initWithCoder:(NSCoder *)aDecoder{
    if(self=[super init])
    {
        _name =[aDecoder decodeObjectForKey:@"name"];
        _salary=[aDecoder decodeFloatForKey:@"salary"];
    }
    return self;

}

Also I have an array with persons, which I want to serialize. But not all the entities. I want to save it partially. I decided to create my own subclass of NSMutableArray which will implement NSCoding protocol and it's own encodeWithCoder and initWithCoder methods:

@interface customNSMutableArray : NSMutableArray<NSCoding>
@end

@implementation customNSMutableArray

-(void)encodeWithCoder:(NSCoder *)aCoder
{
    for(NSObject * obj in self)
    {
        //if(some_condition) 
          [aCoder encodeObject:obj];
    }

}

-(id)initWithCoder:(NSCoder *)aDecoder
{
    //@todo
    return self;
}

@end

And here is a trouble. After trying to encode my customNSMutableArray:

@property customNSMutableArray   *companyStaff;
...
NSData * data=[NSKeyedArchiver archivedDataWithRootObject:_companyStaff];

The encodeWithCoder method in my customNSMutableArray is not invoked. It's directly passed to encodeWithCoder of my Person entities within the array.

How can I serialize NSMutableArray partially?

Answer 1

You can subclass Person into PartialPerson, which you can archive/unarchive.

It's not a good idea to subclass NSMutableArray, and I see no reason for doing so.