Why my own Object not populate NSMutableArray property? - objective-c

Question

Hi i want to implement my own Objects to manage my data, i was trying to make a two classes.
Class Continents that contains a Continent Objects
Here is my implementation:
#implementation OsContinents
#synthesize continentes;
-(id)init{
return [super init];
}
-(NSUInteger)count{
NSLog(#"%u",[continentes count]);
return [continentes count];
}
-(void)add:(OsContinent *)continente{
[continentes addObject:continente];
}
-(OsContinent *)getElementByIndex:(NSUInteger)index{
return [continentes objectAtIndex:index];
}
-(void)deleteContinentByIndex:(NSUInteger)index{
return [continentes removeObjectAtIndex:index];
}
-(void)deleteContinent:(OsContinent *)objContinent{
return [continentes removeObject:objContinent];
}
-(NSMutableArray *)getAll{
return continentes;
}
#end
Next i want to populate *continents Property with "Continent" Objects like this.
OsContinents *continentesCollection = [[OsContinents alloc] init];
for (NSString *strContinente in [data allKeys]) {
OsContinent *con = [[OsContinent alloc] init];
[con setContinente:strContinente];
NSLog(#"%#",[con getContinente]);
[continentesCollection add:con];
}
NSLog(#"%u",[continentesCollection count]);
But allways got ZERO in de count Method.
Note: NSLog(#"%#",[con getContinente]) print de data OK, the Continent Object is OK, the problem is in the "*continentes" inside the Continents Object-
Any Clue?

Answer 1

Your initializer does nothing but initialize the superclass. Use it to set up your own class:
- (id)init
{
self = [super init];
if (self)
{
_continentes = [[NSMutableArray alloc] init];
}
return self;
}
Otherwise, continentes will remain nil. Messaging nil is valid: methods simply don't do anything, and return 0.
If you want to completely hide the underlying mutable array (which is perfectly fine) then don't advertise it in your .h file as a property. Instead, at the beginning of your #implementation, declare a semi-private instance variable:
#implementation OsContinents
{
NSMutableArray *_continentes;
}
I say "semi-private" because you can always use the runtime engine to introspect objects. But it'll be hidden from normal use. If you ever subclass your object, you can always move the instance variable declaration from your #implementation to your #interface so that subclasses can get at it.