iOS: Blocks and ivars

Question

In a lot of question it is asked if its ok to use self in blocks. The answer is no, to avoid retain cycle.

Now when i use an "ivar" in my block in my UIViewController it should be fine. But when i use:

- (void)viewDidLoad
{
    [_customCell setChangedValueBlock:^{
        if(_object != nil){
            NSLog(@"This is a sample");
        }
    }];
}

The dealloc method never called:

-(void)dealloc{
    NSLog(@"Dealloc");
}

When i remove the if(_object != nil){, the dealloc method is called.

Should i make weak reference to the _object before passing it to the block?

Your use of a logged `dealloc` is just the right way to test this. Well done! — matt, May 25 '14 at 21:34

score 5 · Accepted Answer · edited May 23 '17 at 12:10

5

Using an ivar (property, whatever) is exactly like using self - you have implicitly used self. You need to do the weak-strong dance.

It would be much better to pass thru a property, though, because it can be made thread-safe and because accessing an instance variable directly on a released weak reference will cause your device to explode.

edited May 23 '17 at 12:10

Community

1
1

answered May 25 '14 at 21:28

matt

515,959
87
875
1,141

Yes your right, didn't thought of that. Thanks! – Oritm May 25 '14 at 21:33

iOS: Blocks and ivars

1 Answers1