Initializing child objects from parent - objective-c

Question

I'm having a bit of a structural dilemma with designing my app. I want to use a series of nested loops to create a large amount of custom objects. Once those objects are created, I want to store them all into an object which is collection of those objects.
Visualized:
#interface CollectionOfObjectA : NSObject
#property (nonatomic, strong) NSArray *reference;
#end
#implementation CollectionOfObjectA
-(CollectionOfObjectA *)init{
NSMutableArray *ref = [[NSMutableArray alloc] init];
for(int i=0; i < largeNumber; i++){ // There will be nested loops.
NSString *str = #"string made from each loop index";
ObjA *obj = [[ObjA alloc] initWithIndexes: str];
[ref addObject: obj];
}
self.reference = [ref copy];
}
#end
#interface ObjA : CollectionOfObjA
// several properties
#end
#implementation ObjA
-(ObjA *)initWithIndexes:(NSString *)indexes{
self = [super init];
// Use passed indexes to create several properties for this object.
return self;
}
#end
What would be the best way about creating this object which is a collection of child objects? Am I incorrect in making ObjA a child of CollectionOfObjectA -- should it be the other way around? Any help would be greatly appreciated.

Answer 1

Ok, my advise: I have nearly ~30 custom objects. Like events. After that I make class Factory which can create all of them. And also this class Factory have method: getAllObjects.
Like this:
#include "CustomEvent.h"
#interface EventFactory
+(NSArray*)allEvents;
#end
#implementation EventFactory
-(CustomEvent*)firstEvent{/*something here*/}
-(CustomEvent*)secondEvent{/*yes, you should init custom object here*/}
-(CustomEvent*)thirdEvent{/*and after that you can put them*/}
/*
...
*/
+(NSArray*)allEvents{
EventFactory* factory = [[EventFactory alloc]init];
return #[
[factory firstEvent],
[factory secondEvent],
/*...*/
[factory lastEvent]
];
}
#end
Here I return NSArray because I don't need, actually, know anything of them. They already have handlers and they subscribed on custom notifications. You can return NSDictionary for better access.
P.S: for better explanation you can read article in wiki about Factory pattern
But, if you want better manipulation of objects, you should use other pattern:Composite pattern.
What I mean?
#interface EventCollection{
NSMutableArray* YourArray;
}
-(void)addCustomEvent:(CustomEvent*)event atPosition:(NSInteger)position;
-(void)removeCustomEventAtPosition:(NSInteger)position;
-(void)seeAllEvents;
-(void)seeAllPositions; /*if you want*/
-(void)doesThisPositionAvailable:(NSInteger)position;
#end
#implementation EventCollection
-(void)addCustomEvent:(CustomEvent*)event atPosition:(NSInteger)position{
/*maybe you should check if this position available*/
if ([self doesThisPositionAvailable:position]){
/*add element and save position*/
}
}
-(void)removeCustomEventAtPosition:(NSInteger)position{
if (![self doesThisPositionAvailable:position]){
/*destroy element here*/
}
}
-(void)seeAllEvents{
/*yes, this method is the main method, you must store somewhere your objects.
you can use everything, what you want, but don't share your realization.
maybe, you want use array, so, put it as hidden variable. and init at the initialization of your collection
*/
for (CustomEvent* event in YourArray){
[event description];
}
}
#end