I have a series of guns in my game. I use the Gun class/object like this:

(Just an example)

@interface Gun : NSObject
{
    NSString *name; // Six-shooter
    NSNumber *cost;

    NSNumber *clipPrice; // ie: 700
    NSNumber *clipCapacity; // 6
    NSNumber *ammoCapacity; // 6


    NSNumber *damage;   // 0-10

    NSNumber *accuracy; // 0-10
    NSNumber *fireRate; // 0-10
    NSNumber *range;    // 0-10
    // Not sure if I have all the stats, but this is fine for now        
}

Lets say I want to have 3 upgrades per gun. My problem is I am not sure how to do this.

Examples:

• increase fire-rate
• increase range
• increase accuracy
• silencer
• double ammo capacity (ie: Drum)
• double clip capacity (ie: Taped magazine)

Thus my question is, I'd like to implement an upgrade system to guns but I am not sure how to do it.

Would there be an Upgrade object which is a child to the Gun class, or would it be seperate class altogether.

Thanks for your time.