malloc + Automatic Reference Counting?

Question

If I use malloc along with Automatic Reference Counting, do I still have to manually free the memory?

int a[100];
int *b = malloc(sizeof(int) * 100);
free(b);

Answer 1

Yes, you have to code the call to free yourself. However, your pointer may participate in the reference counting system indirectly if you put it in an instance of a reference-counted object:

@interface MyObj : NSObject {
    int *buf;
}
@end

@implementation MyObj

-(id)init {
    self = [super init];
    if (self) {
        buf = malloc(100*sizeof(int));
    }
}
-(void)dealloc {
    free(buf);
}

@end

There is no way around writing that call to free - one way or the other, you have to have it in your code.

Answer 2

Yes. ARC only applies to Objective-C instances, and does not apply to malloc() and free().

Answer 3

Some 'NoCopy' variants of NSData can be paired with a call to malloc which will free you from having to free anything.

NSMutableData can be used as somewhat higher-overhead version of calloc which provides the convenience and safety of ARC.