Question

我有一个创建单独线程的方法：

// Create thread
dispatch_queue_t uniqueQueue = dispatch_queue_create("Unique Email Queue", NULL);

// Run block on another thread called downloadQueue
dispatch_async(uniqueQueue, ^{

     // Save to core data for redundancy
        User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.managedObjectContext];

        coreDataUser.username = [emailStr lowercaseString];
        coreDataUser.email = emailStr;
        coreDataUser.name = nameStr;

        NSError *error;

        if (![self.managedObjectContext save:&error])
        {
            NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
        }            
    }

应用程序总是崩溃在这一行：

User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.managedObjectContext];

我使用本教程作为参考：http://www.codigator.com/tutorials/ios-core-data-tutorial-with-example/

我错过了什么？

Answer 1

NSManagedObjectContext不是线程安全的，尝试在异步块的一侧创建新的moc。尝试：

// Create thread
dispatch_queue_t uniqueQueue = dispatch_queue_create("Unique Email Queue", NULL);

// Run block on another thread called downloadQueue
dispatch_async(uniqueQueue, ^{

     // Save to core data for redundancy
        NSManagedObjectContext *context = [[NSManagedObjectContext alloc] init];
    [context setPersistentStoreCoordinator:persistentStoreCoordinator];

        User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:context];

        coreDataUser.username = [emailStr lowercaseString];
        coreDataUser.email = emailStr;
        coreDataUser.name = nameStr;

        NSError *error;

        if (![context save:&error])
        {
            NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
        }            
    }

持久性商店位于AppDelegate

中

Answer 2

记住 - CoraData不是线程安全的!!!!!

如果你想要managedObjectContext的单独线程，你必须在这个线程上创建一个。要调用正确的上下文，您必须使用performBlock块运行它。在你的情况下：

[self.managedObjectContext performBlock:^{
        User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.managedObjectContext];

        coreDataUser.username = [emailStr lowercaseString];
        coreDataUser.email = emailStr;
        coreDataUser.name = nameStr;

        NSError *error;

        if (![self.managedObjectContext save:&error])
        {
            NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
        }   
}];

但请记住，如果您在mainThread上创建上下文，您的块也会在mainThread上执行。

保存在不同的线程时，应用程序崩溃

2 个答案: