Design issue in Iphone Dev - Generic implementation for Game Bonuses - iphone

Question

So, I thought consulting you guys about my design, cause I sense there might be a better way of doing it.
I need to implement game bonuses mechanism in my app.
Currently there are 9 bonuses available, each one is based of different param of the MainGame Object.
What I had in mind was at app startup to initialize 9 objects of GameBonus while each one will have different SEL (shouldBonus) which will be responsible for checking if the bonus is valid.
So, every end of game I will just run over the bonuses array and call the isBonusValid() function with the MainGame object(which is different after every game).
How's that sound ?
The only issue I have currently, is that I need to make sure that if some bonuses are accepted some other won't (inner stuff)... any advice how to do that and still maintain generic implementation ?
#interface GameBonus : NSObject {
int bonusId;
NSString* name;
NSString* description;
UIImage* img;
SEL shouldBonus;
}
#implementation GameBonus
-(BOOL) isBonusValid(MainGame*)mainGame
{
[self shouldBonus:mainGame];
}
#end

Answer 1

Sounds ok, the only change I would consider is perhaps removing a bonus from the array should it be acepted. That way it is not checked in the future. This would also work for bonus that for other reason should no longer be available.

Answer 2

Whether or not the player can obtain a particular bonus according to the rules of your game isn't something the individual bonuses would know about. This is something the game itself would know. For example, you may have one game that allows bonuses A and B together, but another game that wouldn't.
So the logic to grant or deny a bonus should be in the MainGame object. I would organize it so that GameBonus is a plain bit bucket class and the logic is all in the MainGame. MainGame would be a superclass of any other custom games that might want to override the bonus logic.
A starting point:
typedef enum {
BonusTypeA, BonusTypeB, BonusTypeC
} BonusId;
#interface GameBonus : NSObject {
BonusId bonusId;
NSString *name;
NSString *description;
UIImage *img;
}
#property (nonatomic,assign) BonusId bonusId;
#property (nonatomic,retain) NSString *name;
#property (nonatomic,retain) NSString *description;
#property (nonatomic,retain) NSString *img;
#end
#interface MainGame : NSObject {
NSMutableSet *activeBonuses;
}
-(BOOL) tryToSetBonus:(BonusId)bonus; // tries to set, returns YES if successful.
-(BOOL) isBonusValid:(BonusId)bonus; // has no side effect, just check validity.
#end