Question

I have an object with a property that points to a block:

typedef void (^ThingSetter)();
@property(nonatomic, strong) ThingSetter setup;

I initialize the property with a block. Within the block I refer to the object instance:

Thing *thing = [[Thing alloc] init];

thing.setup = ^() {

    plainOleCFunction(thing.number);
    [thing doSomethingWithString:@"foobar"];
};

However I get compile warnings about a retain loop:

capturing 'thing' strongly in this block is likely to lead to a retain cycle
block will be retained by the captured object

What is the correct way to do this?

Thanks,
Doug

Answer 1

you have to assign thing as weak ref:

Thing *thing = [[Thing alloc] init];
__weak Thing *weakThing = thing;

thing.setup = ^() {

    plainOleCFunction(weakThing.number);
    [weakThing doSomethingWithString:@"foobar"];
};

or you could provide thing as Parameter to the block:

Thing *thing = [[Thing alloc] init];

thing.setup = ^(Thing *localThing) {

    plainOleCFunction(localThing.number);
    [localThing doSomethingWithString:@"foobar"];
};
thing.setup(thing);