ARC模式下的objective-c'lever free'错误

Question

我正在尝试练习块和GCD / NSOperation，所以我编写了这个项目Async-objc，但是当我尝试使用单元测试进行测试时，我总是遇到'双重免费'错误，我以为在ARC模式下不应该有这样的错误。

这是代码

- (void)each:(NSArray *)items iterator:(callbackEach)iterator complete:(callbackWithError)complete {
    NSBlockOperation *blockOp = [NSBlockOperation blockOperationWithBlock:^{
        if (!items || items.count == 0) {
            complete(nil);
            return;
        }

        callbackWithError __block completeOnce = complete;
        NSOperationQueue *queue = [[NSOperationQueue alloc] init];
        NSLog(@"start operations %@", queue);
        [queue setMaxConcurrentOperationCount:kMaxConcurrentOperationCount];
        NSInteger __block count = 0;
        for (id item in items) {
            NSOperation *op = [NSBlockOperation blockOperationWithBlock:^{
                iterator(item, ^(NSError *error) {
                    if (error) {
                        completeOnce(error);
                        completeOnce = nil;
                    } else {
                        count++;
                        if (count >= items.count) {
                            completeOnce(nil);
                            completeOnce = nil;
                        }
                    }
                });
            }];

            [queue addOperation:op];
        }

        [queue waitUntilAllOperationsAreFinished];
        NSLog(@"all operations are down %@", queue);
    }];
    [_mainQueue addOperation:blockOp];
}

这是测试代码：

- (void)testEachWithBigData {
    BOOL __block completed = false;
    NSMutableArray *items = [NSMutableArray arrayWithCapacity:100];
    for (int i = 1; i < 10000; ++i) {
        [items addObject:[NSString stringWithFormat:@"%d", i]];
    }
    NSMutableArray *result = [NSMutableArray arrayWithCapacity:100];
    [_async each:items
        iterator:^(id item, callbackWithError callback) {
            //NSLog(@"======item %@", item);
            NSNumber *num = [NSNumber numberWithInt:[item integerValue]];
            //NSLog(@"number %@", num);
            [result addObject:num];

            callback(nil);
        }
        complete:^(NSError *error) {
            dispatch_async(dispatch_get_main_queue(), ^{
                STAssertNil(error, @"there should be no error");
                [result sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
                    NSNumber *num1 = (NSNumber *)obj1;
                    NSNumber *num2 = (NSNumber *)obj2;
                    if ([num1 integerValue] > [num2 integerValue]) {
                        return NSOrderedDescending;
                    } else if ([num1 integerValue] < [num2 integerValue]) {
                        return NSOrderedAscending;
                    }
                    return NSOrderedSame;
                }];

                NSInteger index = 1;
                for (NSNumber *num in result) {
                    STAssertEquals(index, [num integerValue], @"the value should be ordered");
                    index++;
                }
                completed = YES;
            });
        }
     ];

    NSDate *until = [NSDate dateWithTimeIntervalSinceNow:10];
    while (!completed && [until timeIntervalSinceNow] > 0) {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
                                 beforeDate:until];
    }
}

如果无法重现错误，请将测试项目计数增加到10000。

        for (int i = 1; i < 10000; ++i) {
        [items addObject:[NSString stringWithFormat:@"%d", i]];
    }

和评论NSLog（） 然后Command + U运行单元测试

这是错误消息： 对象0xa0f8000的otest（11105,0xb039f000）malloc： * 错误：未分配被释放的指针

otest（11209,0xb0115000）malloc： *对象0x41dcc00的错误：未释放指针被释放 * 在malloc_error_break中设置断点以进行调试

这次我无法重现'双重免费'错误