Blocks and retain cycle for int variable?

Question

In following code I've created a weak reference to self to avoid retain cycle .Ok The problem is that xCode gives me the same warning "capturing self strongly in this block is likely to lead to a retain cycle" for "currentPage" variable which is an int variable. How come "currentPage" lead to a retain cycle while it is a non objective-c object pointer type

__weak CoresspondenceDetailsViewController *weakself = self;
[tableViewBackground.tableView addInfiniteScrollingWithActionHandler:^
 {
    [weakself getPrivateCorrespondencesForPage:currentPage];
 }

image showing the strange warning.

thank you

Answer 1

The answer is easily! If your variable currentPage is ivar of your view controller then the actual result of accessing this variable will be look like

self->currentPage

which is obviously lead to retaining of self.

Two possible solutions:

__weak CoresspondenceDetailsViewController *weakSelf = self;
int page = currentPage;
[tableViewBackground.tableView addInfiniteScrollingWithActionHandler:^
{
  CoresspondenceDetailsViewController *strongSelf = weakSelf;
  if (strongSelf) {
    [strongSelf getPrivateCorrespondencesForPage:page];
  }
}

or

__weak CoresspondenceDetailsViewController *weakSelf = self;
[tableViewBackground.tableView addInfiniteScrollingWithActionHandler:^
{
  CoresspondenceDetailsViewController *strongSelf = weakSelf;
  if (strongSelf) {
    [strongSelf getPrivateCorrespondencesForPage:strongSelf->currentPage];
  }
}

I updated code, according the lovely comments below. Indeed, it's recommended by Apple way of working with self in blocks.

Answer 2

currentPage seems to be an ivar, thus you get the warning - since accessing an ivar requires an implicit self.

There would be two solutions, which are not strictly equal:

__weak CoresspondenceDetailsViewController *weakself = self;
[tableViewBackground.tableView addInfiniteScrollingWithActionHandler:^
 {
    CoresspondenceDetailsViewController* strongSelf = weakSelf;
    [strongSelf getPrivateCorrespondencesForPage:strongSelf.currentPage];
 }

or

NSInteger cp = self.currentPage;
__weak CoresspondenceDetailsViewController *weakself = self;
[tableViewBackground.tableView addInfiniteScrollingWithActionHandler:^
 {
    CoresspondenceDetailsViewController* strongSelf = weakSelf;
    [strongSelf getPrivateCorrespondencesForPage:cp];
 }

Answer 3

请尝试以下方法：

__unsafe_unretained typeof(self) weakSelf = self