为什么这里有保留周期？

Question

Here is the code from Ray tutorial about ReactiveCocoa and I can't figure out how come it has retain cycle, can someone indicate that?

- (RACSignal *)signalForSearchWithText:(NSString *)text {

    // 1 - define the errors
    NSError *noAccountsError = [NSError errorWithDomain:RWTwitterInstantDomain
                                                   code:RWTwitterInstantErrorNoTwitterAccounts
                                               userInfo:nil];

    NSError *invalidResponseError = [NSError errorWithDomain:RWTwitterInstantDomain
                                                        code:RWTwitterInstantErrorInvalidResponse
                                                    userInfo:nil];

    // 2 - create the signal block
    @weakify(self)
    return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
        @strongify(self);
        // 3 - create the request
        SLRequest *request = [self requestforTwitterSearchWithText:text];

        // 4 - supply a twitter account
        NSArray *twitterAccounts = [self.accountStore
                                    accountsWithAccountType:self.twitterAccountType];
        if (twitterAccounts.count == 0) {
            [subscriber sendError:noAccountsError];
        } else {
            [request setAccount:[twitterAccounts lastObject]];

            // 5 - perform the request
            [request performRequestWithHandler: ^(NSData *responseData,
                                                  NSHTTPURLResponse *urlResponse, NSError *error) {
                if (urlResponse.statusCode == 200) {

                    // 6 - on success, parse the response
                    NSDictionary *timelineData =
                    [NSJSONSerialization JSONObjectWithData:responseData
                                                    options:NSJSONReadingAllowFragments
                                                      error:nil];
                    [subscriber sendNext:timelineData];
                    [subscriber sendCompleted];
                }
                else {
                    // 7 - send an error on failure
                    [subscriber sendError:invalidResponseError];
                }
            }];
        }

        return nil;
    }];
}

Because I am trying to remove @weakify(self) and @stringify(self)

Answer 1

There isn't an obvious retain cycle in this code. You ought to be able to remove the @weakify/@strongify usages without a problem.

Answer 2

In block , u shouldn't use self directly. self keeps a block instance and the block keeps self. U can use a weak self in block to avoid the retain cycle.