为什么使用ivar会导致反应性可可中的保留周期？

Question

I use an ivar in a reactive cocoa's block, set weakify(self) and strongify(self) to break the retain cycle. But when I run the code, It causes a memory leak, the controller doesn't call dealloc method. If I change the ivar to an property, it runs right. I'm so confused about it and search for a long time. please tell me why.

- (void)viewDidLoad {
     [super viewDidLoad];
     ...
     @weakify(self);
     [RACObserve(self, something) subscribeNext:^(id x) {
         @strongify(self);
         [_button setBackgroundColor:[UIColor redColor]];
     }];
}

- (void)dealloc {

}

Answer 1

@strongify(self)以名称self声明新变量，并在调用self.button时使用此新变量， _button隐式使用请勿覆盖self