按 BETWEEN 属性过滤核心数据结果

Question

我目前有 Core Data 成功返回了名为 Event 的特定实体的所有结果：

NSManagedObjectContext *context = [delegate managedObjectContext];
NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"Event" 
                                                     inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDescription];

NSError *error;
NSArray *fetchResults = [context executeFetchRequest:request error:&error];

现在在日历绘制时，我需要获取开始日期在本月或之前且结束日期也在本月或之后的事件。

我相信答案与 NSPredicate 有关，但我对它还不够熟悉，无法让它服从我的意愿。

Answer 1

将条件改为谓词：

NSDate * firstDateOfMonth = [self returnDateForMonth:month year:year day:2];
NSDate * lastDateOfMonth = [self returnDateForMonth:month+1 year:year day:1];

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(startDate => firstDateOfMonth) and (endDate <= lastDateOfMonth)”];

NSManagedObjectContext *context = [delegate managedObjectContext];

NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"Event"                                              inManagedObjectContext:context];

NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDescription];
[request setPredicate:predicate];

NSError *error;

NSArray *fetchResults = [context executeFetchRequest:request error:&error];