does NSURLConnection block method has circular reference problem? Result is no.

NSURLConnectionRetainTest.m

#import <Foundation/Foundation.h>

@interface BlockTest : NSObject
-(void)request;
@end

@implementation BlockTest {
    NSOperationQueue *_queue;
    NSString *_str;
}

- (id)init
{
    self = [super init];
    if (self) {
        _queue = [[NSOperationQueue alloc] init];
        _str = @"hoge";
    }
    return self;
}

-(void)request {
    NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.hatena.ne.jp"]];
    [NSURLConnection sendAsynchronousRequest:req queue:_queue completionHandler:^(NSURLResponse *res, NSData *data, NSError *error) {
        NSLog(@"%@", _str);
    }];
}

@end

int main(int argc, const char * argv[])
{
    @autoreleasepool {
        BlockTest *test = [[BlockTest alloc] init];
        [test request];
        NSLog(@"retain %ld", CFGetRetainCount((__bridge CFTypeRef) test)); // => retain 2
        [NSThread sleepForTimeInterval:1];
        NSLog(@"retain %ld", CFGetRetainCount((__bridge CFTypeRef) test)); // => retain 1
    }

    return 0;
}