CODEWITHSUNDEEP
objective-cmallocautomatic-ref-counting
Stas Jaro
Stas Jaro

Reputation: 4885

malloc + Automatic Reference Counting?

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);

Upvotes: 10

Views: 7561

Answers (4)

Integer Poet
Integer Poet

Reputation: 747

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.

Upvotes: 1

Gary Davies
Gary Davies

Reputation: 960

In dealloc add an if not nil and assign to nil for safe. Dont want to free nil, malloc might be used outside of init etc.

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

@implementation MyObj

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

-(void)dealloc {
    if(buf != null) {
        free(buf);
        buf = null;
    }
}

@end

Upvotes: 0

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 727077

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.

Upvotes: 21

Greg Hewgill
Greg Hewgill

Reputation: 994817

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

Upvotes: 4

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