iOS 简单谓词 'contains' 不工作

Question

我有一个模型:

地点<--->>类别

执行以下查询时:

NSFetchRequest *req = [NSFetchRequest fetchRequestWithEntityName:@"Category"];
if(![searchText isEqualToString:@""] && searchText != nil){
    req.predicate = [NSPredicate predicateWithFormat:@"(places.placeTitle contains %@) OR (places.details contains %@) OR (name contains %@)", searchText, searchText, searchText];
    NSLog(@"ModelHelper.getResults: Search text given, creating predicate: %@", req.predicate);
}
req.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"name"
                                                                             ascending:YES
                                                                              selector:@selector(localizedCaseInsensitiveCompare:)]];
NSFetchedResultsController *controller = [[NSFetchedResultsController alloc]initWithFetchRequest:req
                                                                            managedObjectContext:context
                                                                              sectionNameKeyPath:nil
                                                                                       cacheName:nil];
NSError *error = nil;
[controller performFetch:&error];

我收到不应该出现的匹配项，例如:

searchText = "1234"

第一个结果是:

category[0].name = "Bars"
category[0].places[0].placeTitle = "Aaa"
category[0].places[0].details = "Aaa"
category[0].places[1].placeTitle = "123456"
category[0].places[1].details = "123456"
category[0].places[2].placeTitle = "test"
category[0].places[2].details = "test"

我的谓词有什么地方做错了吗？谢谢。

Answer 1

来自documentation :

Important: You must not modify fetchRequest after invoking this method. For example, you must not change its predicate or the sort orderings.

移动这个片段:

if(![searchText isEqualToString:@""] && searchText != nil){
    req.predicate = [NSPredicate predicateWithFormat:@"(places.placeTitle contains[c] %@) OR (places.details contains[c] %@) OR (name contains[c] %@)", searchText, searchText, searchText];
    NSLog(@"ModelHelper.getResults: Search text given, creating predicate: %@", req.predicate);
}

在初始化 FRC 之前