NSPredicate with multiple statements

Question

我有NSPredicate四個語句/參數。似乎所有這些都不是「包含」的。它看起來像這樣：

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

看起來像最後一部分：&& postId >= %d，被忽略。如果我嘗試：

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

我得到相同的結果（應該是0）。我不知道這樣的謂詞應該看起來如何？

Answer 1

正如在討論橫空出世，真正的問題是，謂語是 使用讀取的結果控制器，並在一段時間內改變謂詞中使用的變量。

在這種情況下，您必須重新創建謂詞和獲取請求。這在NSFetchedResultsController Class Reference的「修改提取請求」中記錄爲 。

你的情況

所以，如果self.currentMinId變化，你應該

// 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

你可以試試下面的代碼嗎？

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]];