Question

修改

好的，我想我已经明白了。

我的整体操作流程如下：

-(void)submitRegistration
{    
    //[[AppDelegate sharedDelegate] drupalLogin];

    [self validateFields];

    if(fieldsValid)
    {
        [self createBike];

        // save member node will save bike node too if successful
        // bike node will not be saved if member node did not save successful
        [self saveMemberNode];

        // save the updated member node and bike node to Core Data
        [self saveLocalRegistration]; 
        // *** ABOVE LINE GETS EXECUTED BEFORE ASYNC REQUEST FINISHES ***
    }
}

我的“[self saveLocalRegistration];”代码在异步请求“Block”完成执行之前执行，导致它崩溃。

“saveLocalRegistration”方法调用[managedObjectContext save：＆amp; error];

原始问题

刚刚第一次潜入核心数据。

在我的应用程序中，我要做的一件事就是将一些数据发送到Drupal服务器。

我已将问题缩小到这个范围：

// *** *** *** 
// doesn't crash here
// *** *** ***
NSLog(@"bike.brand = %@", bike.brand);
NSLog(@"bike.model = %@", bike.model);
NSLog(@"bike.features = %@", bike.features);

// save new member node to Drupal
[DIOSNode nodeSave:memberData success:^(AFHTTPRequestOperation *operation, id responseObject) 
 {
     NSLog(@"Node saved!");
     NSDictionary *serverNodeData = (NSDictionary *)responseObject;

     NSLog(@"Server node details = %@", serverNodeData);

     // set the member's memberId to the newly created Drupal member node's nodeId
     member.memberId = [NSNumber numberWithLong:[[serverNodeData valueForKey:@"nid"] longLongValue]];

     // *** *** ***
     // accessing bike properties here inside this objective c "Block" crashes app
     // somehow the above line "member.memberId = .... " doesn't crash despite both being Core Data entities
     // *** *** ***
     NSLog(@"bike.brand = %@", bike.brand); // <--- CRASH HERE ***
     NSLog(@"bike.model = %@", bike.model);
     NSLog(@"bike.features = %@", bike.features);

     //bike.ownerId = member.memberId;

     // save bike node with member id
     [self saveBikeNode];
 } 
           failure:^(AFHTTPRequestOperation *operation, NSError *error) 
 {
     NSLog(@"Failed to save node, error: %@", [error localizedDescription]);
 }];

从上面的源代码中可以看出，NSLogs的第一个块不会使应用程序崩溃，但是在目标c“Block”内，同一块NSLog会崩溃应用程序。

注意：“[DIOSNode nodeSave：memberData success：....”Objective C块是我认为的异步请求。不知道这是否是一个多线程问题。

bike.brand，bike.model和bike.features是“String”数据类型。

Answer 1

在块外声明这个并在块内使用它而不是'self'

__block <classname> *blocksafeSelf = self;

Answer 2

我可以通过在崩溃之前查看调试器的状态来确认，但我的理解是您从不属于它的线程访问托管对象。

您必须在托管对象上下文设计的队列（performBlock和performBlockAndWait）上安排成功块。

Block崩溃中的Core Data对象属性访问

修改

原始问题

2 个答案: