ios - 调用核心数据操作时崩溃并显示 "failed to scene-update in time"消息

Question

我遇到了一个奇怪的问题“未能及时更新场景”。下载数据后，我将其存储到核心数据中。如果应用程序在前台，一切都会正常工作。仅当我在将数据存储到核心数据的过程中连续在状态、后台和前台之间切换应用程序时，才会出现此崩溃。在 Debug模式下不会发生此崩溃。

我尝试将日志放在 Core Data 操作方法的不同阶段，我发现了应用程序实际崩溃的地方。在用户界面中，我使用以下代码

DatabaseManagerClass *database = [[DatabaseManagerClass alloc]init];
[database deleteDataFromFormTable:nil];

[database insertDataInChecklistTable:[self.responseDictionary valueForKey:@"checklists"]];

[self performSelectorOnMainThread:@selector(mainThreadTask) withObject:nil waitUntilDone:YES];`

崩溃发生在“insertDataInChecklistTable”方法内部。我检查了 insertDataInChecklistTable 在其中工作的线程。它仅在主线程中。任何人都可以提出一些建议来解决这个问题。

提前致谢，谢里。

带有执行 block 的更新代码

-(void)insertDataInFormColumnsTable:(NSMutableArray*)responseArray withForm:(Form*)form

{ AppDelegate objAppDelegate = (AppDelegate)[[UIApplication sharedApplication] delegate];

NSManagedObjectContext *moc   = [objAppDelegate managedObjectContext];
NSManagedObjectContext *bgMOC = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];

[bgMOC performBlock:^{
    for (int count=0; count<[responseArray count]; count++)
    {
        NSDictionary *columnDict = [responseArray objectAtIndex:count];

        Form_Column *formColumn = [NSEntityDescription insertNewObjectForEntityForName:@"Form_Column" inManagedObjectContext:moc];


        if ([columnDict valueForKey:FORMULA]!=[NSNull null])        //Added by mritunjay
            formColumn.formula = [columnDict valueForKey:FORMULA];
        else
            formColumn.formula=nil;

        if ([columnDict valueForKey:ASP_EDITABLE]!=[NSNull null])
            formColumn.asp_editable = [columnDict valueForKey:ASP_EDITABLE];
        else
            formColumn.asp_editable=nil;


        if ([columnDict valueForKey:CM_EDITABLE]!=[NSNull null])
            formColumn.cm_editable = [columnDict valueForKey:CM_EDITABLE];
        else
            formColumn.cm_editable=nil;

        if ([columnDict valueForKey:IM_EDITABLE]!=[NSNull null])
            formColumn.im_editable = [columnDict valueForKey:IM_EDITABLE];
        else
            formColumn.im_editable=nil;


        if ([columnDict valueForKey:SP_EDITABLE]!=[NSNull null])
            formColumn.sp_editable = [columnDict valueForKey:SP_EDITABLE];
        else
            formColumn.sp_editable=nil;

        if ([columnDict valueForKey:ASP_EDITABLE]!=[NSNull null])
            formColumn.dialog_row = [columnDict valueForKey:ASP_EDITABLE];
        else
            formColumn.dialog_row=nil;

        if ([columnDict valueForKey:INDEX]!=[NSNull null])
            formColumn.index = [columnDict valueForKey:INDEX];
        else
            formColumn.index=nil;

        if ([columnDict valueForKey:WEB_ONLY]!=[NSNull null])
            formColumn.web_only = [columnDict valueForKey:WEB_ONLY];
        else
            formColumn.web_only=nil;

        if ([columnDict valueForKey:LABEL]!=[NSNull null])
            formColumn.label = [columnDict valueForKey:LABEL];
        else
            formColumn.label=nil;

        formColumn.form_id = form.form_id;

        if ([columnDict valueForKey:ID]!=[NSNull null])
            formColumn.column_id=[columnDict valueForKey:ID];
        else
            formColumn.column_id=nil;

        if ([columnDict valueForKey:TYPE]!=[NSNull null])
            formColumn.type=[columnDict valueForKey:TYPE];
        else
            formColumn.type=nil;

        NSArray *selectionArray = [columnDict valueForKey:SELECTIONS];

        if ([selectionArray count]) {


            for (int count = 0; count < [selectionArray count]; count++)
            {
                Form_Sub_Columns *formSubColumns = [NSEntityDescription insertNewObjectForEntityForName:@"Form_Sub_Columns" inManagedObjectContext:moc];

                NSDictionary *subColumnDict = [selectionArray objectAtIndex:count];

                if ([subColumnDict valueForKey:ID]!=[NSNull null])
                    formSubColumns.column_id=[subColumnDict valueForKey:ID];
                else
                    formSubColumns.column_id=nil;

                if ([subColumnDict valueForKey:LABEL]!=[NSNull null])
                    formSubColumns.label=[subColumnDict valueForKey:LABEL];
                else
                    formSubColumns.label=nil;

                if ([subColumnDict valueForKey:REQUIRES_REMARKS]!=[NSNull null])
                    formSubColumns.requires_remarks=[subColumnDict valueForKey:REQUIRES_REMARKS];
                else
                    formSubColumns.requires_remarks=nil;


                if ([subColumnDict valueForKey:VALUE]!=[NSNull null])
                    formSubColumns.value=[subColumnDict valueForKey:VALUE];
                else
                    formSubColumns.value=nil;


                if ([subColumnDict valueForKey:DESCRIPTION]!=[NSNull null])
                    formSubColumns.description_name=[subColumnDict valueForKey:DESCRIPTION];
                else
                    formSubColumns.description_name=nil;



                if ([subColumnDict valueForKey:SELECTION_TYPE_ID]!=[NSNull null])
                    formSubColumns.selection_type_id=[subColumnDict valueForKey:SELECTION_TYPE_ID];
                else
                    formSubColumns.value=nil;

                [formColumn addSun_columnsObject:formSubColumns];
            }
        }
        [formColumn addFormObject:form];

        [form addColumnsObject:formColumn];

    }

    if([form.enable_attachment boolValue])
    {
        Form_Column *formColumn = [NSEntityDescription insertNewObjectForEntityForName:@"Form_Column" inManagedObjectContext:moc];

        formColumn.label = @"Add Attachments";

        formColumn.form_id = form.form_id;
        formColumn.index = [NSNumber numberWithInt:998];
        formColumn.column_id=[NSNumber numberWithInt:998];    // hardcoded if Attachment is Enabled.
        formColumn.web_only = [NSNumber numberWithInt:0];
        formColumn.type=[NSNumber numberWithInt:-1];

        [form addColumnsObject:formColumn];

    }

    if ([[NSThread currentThread] isMainThread]) {
        NSLog(@"Main Thread inside block");
    }
    else {
        NSLog(@"Not main thread inside block");
    }

    NSError *error;

    if(![bgMOC save:&error]){
        NSLog(@"Error %@", [error localizedDescription]);
    }
}];

Answer 1

在主/UI 线程上处理数据总是是个坏主意，会导致这样的问题。

您的 -insertDataIntoChecklistTable 需要在后台队列上运行，这意味着您应该:

1. 创建第二个 NSManagedObjectContext，它是一个 NSPrivateQueueConcurrencyType
2. 将其与您的主要背景相关联
3. 使用 -performBlock: 处理针对 NSManagedObjectContext 的数据
4. 处理完成后保存

这将使您的数据处理脱离主队列。永远不要处理主队列上的数据。