Iphone 获取最近30条记录coredata NSPredicate

我想从coredata中获取最后30条记录，我想使用NSPredicate:目前

NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:managedContext];
[request setEntity:entity];

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"((from == %@) AND (to == %@) )OR((from == %@) AND (to == %@))",from, to,to ,from];
[request setPredicate:predicate];


NSError *error = nil;
NSMutableArray *mutableFetchResults = [[managedContext
                                        executeFetchRequest:request
                                        error:&error] mutableCopy];

如何添加用于将其调整到正确顺序并将设置为30的方法

使用将其设置为正确的顺序，并将其设置为30

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我想fetchOffset是我的需要我想fetchOffset是我的需要

NSSortDescriptor* fromSortDescriptor = [[NSSortDescriptor alloc]
                            initWithKey:@"from" ascending:YES];
[request setSortDescriptors:@[fromSortDescriptor]];
[request setFetchLimit:30];