Question

If you initialize an NSMutableArray with NSArray’s convenience method as above, do you get an NSArray or an NSMutableArray?

Any consequences?

(I know that NSMutableArray has “arrayWithCapacity:, I’m just curious)

Answer 1

If you initialize it using:

NSMutableArray *array = [NSMutableArray array];

you get a NSMutableArray. One great feature of Objective-C is that class methods are inherited by subclasses.

So, in a class method you can do something like this:

+(id)array {
    return [[[self alloc] init] autorelease];
}

and self will be referencing to the class object where the code is executing (NSArray or NSMutableArray).