ios - Dereferencing a __weak pointer is not allowed inside block -

apple docs can avoid strong reference cycle capturing weak reference self, this:

- (void)configureblock {     xyzblockkeeper * __weak weakself = self;     self.block = ^{         [weakself dosomething];   // capture weak reference                                   // avoid reference cycle     } } 

yet when write code, compiler tells me:

dereferencing __weak pointer not allowed due possible null value caused race condition, assign strong variable first

yet doesn't following code create strong reference cycle, , possibly leak memory?

- (void)configureblock {     xyzblockkeeper *strongself = self;     self.block = ^{         [strongself dosomething];     } } 

you should use one: eg:

__weak xyzblockkeeper *weakself = self;  self.block = ^{      xyzblockkeeper *strongself = weakself;      if (strongself) {         [strongself dosomething];     } else {         // bummer.  <self> dealloc before run code.     } }