ios - iOS核心数据在后台获取导致崩溃

Question

在我的应用程序中，我一直在后台进行Core Data工作。
Testflight一直在报告特定的提取操作发生了很多崩溃，该操作从Core Data获取了当前登录的环境对象(我无法复制):

- (Environment *)getActiveEnvironment
{
    AppDelegate *ad = [AppDelegate sharedAppDelegate];
    NSManagedObjectContext *context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
    [context setParentContext:ad.managedObjectContext];
    
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Environment" inManagedObjectContext:context];
    [fetchRequest setEntity:entity];
    
    NSError *error;

    //crash points to this line
    NSArray *items = [context executeFetchRequest:fetchRequest error:&error];
    
    Environment *tempE = nil;
    if(items.count > 0)
    {
        for(Environment *e in items)
        {
            if(!e.token && !e.url)
            {
                break;
            }
            
            Environment *mainContextTv = (Environment *)[ad.managedObjectContext objectWithID:e.objectID];
            if(e.activeValue)
                 tempE = mainContextTv;                
        }  
    }

    return tempE;
}

这是我从Testflight收到的崩溃堆栈:

0   Tower-iSales-Tab    0x002b37b2  testflight_backtrace
1   Tower-iSales-Tab    0x002b2e4a  TFSignalHandler
2   libsystem_platform.dylib    0x39144722  _sigtramp
3   CoreData    0x2e1b8cec  _perform
4   CoreData    0x2e1c30f4  -[NSManagedObjectContext(_NestedContextSupport) executeRequest:withContext:error:]
5   CoreData    0x2e13477a  -[NSManagedObjectContext executeFetchRequest:error:]
6   Tower-iSales-Tab    0x000c7082  -[MySingleton getActiveEnvironment] in MySingleton.m on Line 379
7   Tower-iSales-Tab    0x000c73f8  -[MySingleton getToken] in MySingleton.m on Line 416
8   Tower-iSales-Tab    0x0020c476  -[NetworkManager getPathForViewName:useTimeStamp:timeStamp:index:counter:] in NetworkManager.m on Line 699
9   Tower-iSales-Tab    0x0020aa5a  __70-[NetworkManager checkForDataFilesShouldEmptyQueue:isInitialDownload:]_block_invoke167 in NetworkManager.m on Line 415
10  libdispatch.dylib   0x3901b8fa  _dispatch_barrier_sync_f_invoke
11  Tower-iSales-Tab    0x0020a33e  __70-[NetworkManager checkForDataFilesShouldEmptyQueue:isInitialDownload:]_block_invoke113 in NetworkManager.m on Line 335
12  libdispatch.dylib   0x39017102  _dispatch_call_block_and_release
13  libdispatch.dylib   0x3901c7e4  _dispatch_root_queue_drain
14  libdispatch.dylib   0x3901c9d0  _dispatch_worker_thread2
15  libsystem_pthread.dylib 0x39146dfe  _pthread_wqthread
16  libsystem_pthread.dylib 0x39146cc3  start_wqthread

我读了this answer，它建议将队列类型设置为NSPrivateQueueConcurrencyType，而不是我可以做的NSConfinementConcurrencyType，但这不是我可以轻松复制的崩溃，因此我想确定会导致崩溃的原因。
该答案还建议将performBlockAndWait块用于后台获取，但是在我的函数中我将如何？我需要返回一个Environment对象，我在整个应用程序中都使用了此函数。
谢谢

Answer 1

据我了解，您不必在这里使用NSConfinementConcurrencyType上下文，因为您仅从主线程调用-getActiveEnvironment。因此，您可以在主上下文(ad.managedObjectContext)上执行所有操作。

然后应仅从主线程访问返回的对象。如果要从其他线程访问它，则必须使用objectWithID:在与该线程关联的上下文中获取它。