Question

我正在尝试删除所有对象，但我似乎无法使其正常工作。我知道这类问题还有其他问题，但它们没有帮助。我想要的是删除此方法中的section和fixture实体中的所有对象。

- (void)refresh:(UIRefreshControl *)refreshControl {    
    [refreshControl endRefreshing];
}

这是我用另一种方法保存和获取对象的地方。

NSManagedObjectContext *context = [self managedObjectContext];

for (int i=0; i <=fixtures.count-1; i++) {

    fixture = [NSEntityDescription insertNewObjectForEntityForName:@"Fixture" inManagedObjectContext:context];

    [fixture setValue:[NSString stringWithFormat:@"%@",[[fixtures objectAtIndex:i] objectForKey:@"date"]] forKey:@"date"];
    [fixture setValue:[[fixtures objectAtIndex:i] objectForKey:@"time"] forKey:@"time"];
    [fixture setValue:[[fixtures objectAtIndex:i] objectForKey:@"home"] forKey:@"home"];
    [fixture setValue:[[fixtures objectAtIndex:i] objectForKey:@"away"] forKey:@"away"];
    [fixture setValue:[[fixtures objectAtIndex:i] objectForKey:@"league"] forKey:@"league"];
}

for (int i=0; i <=sections.count-1; i++) {
    lolSection = [NSEntityDescription insertNewObjectForEntityForName:@"Section" inManagedObjectContext:context];
    [lolSection setValue:[NSString stringWithFormat:@"%@",[[sections objectAtIndex:i] objectForKey:@"date"]] forKey:@"date"];
}

NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Fixture"];
self.theFixtures = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];

NSFetchRequest *fetchRequest2 = [[NSFetchRequest alloc] initWithEntityName:@"Section"];
self.theSection= [[managedObjectContext executeFetchRequest:fetchRequest2 error:nil] mutableCopy];

NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:@"self" ascending:NO];
NSArray *descriptors = [NSArray arrayWithObject: descriptor];
NSArray* reverseTheArray = [[self.theSection valueForKey:@"date"] sortedArrayUsingDescriptors:descriptors];
reversedArray = [[reverseTheArray reverseObjectEnumerator] allObjects];

Answer 1

那么，到目前为止你尝试了什么？

根据文件。

删除托管对象非常简单。你只需发送它托管对象上下文deleteObject:消息，传递对象想删除作为参数。

换句话说，使用有效的上下文，你应该说

[aValidContext deleteObject:managedObjectYouWantToDelete];

关于您的问题，您需要

设置抓取请求以抓取Fixture个项目
循环结果（NSArray）并执行删除

例如

NSFetchRequest* request = // create the request here...

NSError *error;
NSArray *array = [aValidContext executeFetchRequest:request error:&error];
if (array == nil) {
    // Deal with error...
} else {
    // loop the array performing deleteObject
}

// save to persistent store

剩下的代码留给练习;）

修改1

再次阅读您的问题，Section和Fixture之间的关系是什么？如果它们是分隔的实体，则还应对Section s执行先前的步骤。

从另一个方法中删除NSManagedObjectContext中的对象

1 个答案: