NSPredicate with multiple statements

Question

我有NSPredicate四个语句/参数。似乎所有这些都不是“包含”的。它看起来像这样：

predicate = [NSPredicate predicateWithFormat:@"user.youFollow = 1 || user.userId = %@ && user.youMuted = 0 && postId >= %d", [AppController sharedAppController].currentUser.userId, self.currentMinId.integerValue]; 

看起来像最后一部分：&& postId >= %d，被忽略。如果我尝试：

predicate = [NSPredicate predicateWithFormat:@"user.youFollow = 1 || user.userId = %@ && user.youMuted = 0 && postId = 0", [AppController sharedAppController].currentUser.userId, self.currentMinId.integerValue]; 

我得到相同的结果（应该是0）。我不知道这样的谓词应该看起来如何？

Answer 1

正如在讨论横空出世，真正的问题是，谓语是 使用读取的结果控制器，并在一段时间内改变谓词中使用的变量。

在这种情况下，您必须重新创建谓词和获取请求。这在NSFetchedResultsController Class Reference的“修改提取请求”中记录为 。

你的情况

所以，如果self.currentMinId变化，你应该

// create a new predicate with the updated variables: 
NSPredicate *predicate = [NSPredicate predicateWithFormat:...] 
// create a new fetch request: 
NSFetchRequest *fetchRequest = ... 
[fetchRequest setPredicate:predicate]; 

// Delete the section cache if you use one (better don't use one!) 
[self.fetchedResultsController deleteCacheWithName:...]; 

// Assign the new fetch request and re-fetch the data: 
self.fetchedResultsController.fetchRequest = fetchRequest; 
[self.fetchedResultsController performFetch:&error]; 

// Reload the table view: 
[self.tableView reloadData]; 

Answer 2

你可以试试下面的代码吗？

NSPredicate *youFollowPred = [NSPredicate predicateWithFormat:@"user.youFollow == 1"]; 
NSPredicate *userIdPred = [NSPredicate predicateWithFormat:@"user.userId == %@",[AppController sharedAppController].currentUser.userId]; 
NSPredicate *youMutedPred = [NSPredicate predicateWithFormat:@"user.youMuted == 0"]; 
NSPredicate *postIdPred = [NSPredicate predicateWithFormat:@"postId >= %d", self.currentMinId.integerValue]; 

NSPredicate *orPred = [NSCompoundPredicate orPredicateWithSubpredicates:[NSArray arrayWithObjects:youFollowPred,userIdPred, nil]]; 

NSPredicate *andPred = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:youMutedPred,postIdPred, nil]]; 

NSPredicate *finalPred = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:orPred,andPred, nil]];