Question

I have an ivar like this declared on interface:

BOOL controllerOK;

I have to use this ivar inside a block that resides itself in a block. Something like

myBlockl = ^(){
  [self presentViewController:controller
    animated:YES
    completion:^(){
      if (controllerOK)
        [self doStuff];
      }];
};

If I try to do that, I see a warning:

capturing self strongly in this block is likely to lead to a retain cycle

for the if (controllerOK) line.

This does not appear to be one of those blocks problems that you create another variable using __unsafe_unretained before the block starts. First because this instruction cannot be used with a BOOL and second because the ivar controllerOK has to be tested on runtime inside the block. Another problem is that the block itself is declared on the interface, so it will be used outside the context where it is being created.

How do I solve that?

Answer 1

This should work:

__weak id this = self;
myBlockl = ^(){
  [self presentViewController:controller
    animated:YES
    completion:^(){
      if (this->controllerOK)
        [this doStuff];
      }];
};