看看这段代码有没有循环引用？``` self.person = [[ZNZPerson alloc] init]; __

self.person = [[ZNZPerson alloc] init];
__weak typeof(self) weakSelf = self;
self.person.block = ^{
    __strong typeof(weakSelf) strongSelf = weakSelf;
    [strongSelf _test];
    strongSelf.person1 = [[ZNZPerson alloc] init];
    strongSelf.person1.block = ^{
        [strongSelf _test];
    };        
    ZNZStaticInstance *instance = [ZNZStaticInstance sharedInstance];
    instance.block = ^{
        [strongSelf _test];
    };
    [instance doSth:^{
        [self _test];
     }];
};