NSFetchedResultsController 错误：索引 X 处获取的对象有一个无序的节名称 Y。对象必须按节名称排序
我正在 iPhone 应用程序中实现搜索栏。我有工人列表，每个工人都有属性：名字、姓氏、公司。表视图的部分设置为公司属性。
我在搜索时确实设置了谓词：
NSPredicate *predicate =[NSPredicate predicateWithFormat:@"firstName contains[cd] %@", searchBar.text];
并且收到错误：
NSFetchedResultsController ERROR: The fetched object at index 3 has an out of order section name 'company2. Objects must be sorted by section name'
当我有 sortDescriptor: 时，
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"lastName" ascending:YES selector:@selector(caseInsensitiveCompare:)];
我确实注意到，当我将其更改为
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"firstName"` ascending:YES selector:@selector(caseInsensitiveCompare:)];
现在时，搜索可以正常工作，没有错误。 initWithKey 参数是否必须与谓词中的属性名称匹配？我不明白。
I'm implementing search bar in iphone app. I have list of Workers, each have attributes: firstName, lastName, company. Sections of table view are set to company attribute.
I did set predicate when searching:
NSPredicate *predicate =[NSPredicate predicateWithFormat:@"firstName contains[cd] %@", searchBar.text];
and i get error:
NSFetchedResultsController ERROR: The fetched object at index 3 has an out of order section name 'company2. Objects must be sorted by section name'
when I have sortDescriptor:
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"lastName" ascending:YES selector:@selector(caseInsensitiveCompare:)];
I did notice that when I change it to
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"firstName"` ascending:YES selector:@selector(caseInsensitiveCompare:)];
now search works correctly with no error. Does initWithKey param must match attribute name in predicate? I don't get it.
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来自 NSFetchedResultsController 文档：
在您的情况下，您需要使用两种排序（在数组中）。第一个元素应该根据公司名称属性进行排序，第二个元素应该根据lastName/firstName 属性进行排序。
From the NSFetchedResultsController docs:
In your case, you need to use two sorts (in an array.) Element one should be a sort on the company name attribute and second element should sort on the lastName/firstName attribute.