如果我数据模型定义了一个Teacher, 还有一个Student.Teacher和Student是一对多的关系.关系类似于这样:student.whoTeach = teacher;我想问在使用UITableView的时候,我想通过predicate,把所有是同一个Teacher的Student返回到NSFetchedResultsController里面,然后再在TableView里面显示出来,predicate该怎么写呢??下面是我写的一段代码:
NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"Student"];
request.predicate = [NSPredicate predicateWithFormat:]; // 这里不知道怎么写!!!!!!
_fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
_fetchedResultsController.delegate = self;
如果这种方法行不通的话,还有其他方法吗?
NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"Student"];
request.predicate = [NSPredicate predicateWithFormat:]; // 这里不知道怎么写!!!!!!
_fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
_fetchedResultsController.delegate = self;
如果这种方法行不通的话,还有其他方法吗?
request.predicate = [NSPredicate predicateWithBlock:^BOOL(Student * evaluatedObject, NSDictionary *bindings) {
if (evaluatedObject.whoTeach.teacherID == aTeacher.teacherID) {
return YES;
}
return NO;
}];