本文介绍了核心数据NSFetchRequest setResultType：NSDictionaryResultType不工作的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
将NSFetchRequest结果类型设置为NSDictinaryResultType时，将返回零个对象。如果我删除setPropertiesToFetch和setResultType，则返回所有对象。
When setting a NSFetchRequest result type to NSDictinaryResultType, zero objects are returned. If I remove setPropertiesToFetch and setResultType, all the objects are returned.
任何想法？
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Alert" inManagedObjectContext:_managedObjectContext];
[request setEntity:entity];
NSDictionary *entityProperties = [entity propertiesByName];
[request setPropertiesToFetch:[NSArray arrayWithObject:[entityProperties objectForKey:@"test"]]];
[request setResultType:NSDictionaryResultType];
NSError *error;
NSArray *result = [_managedObjectContext executeFetchRequest:request error:&error];
if (result == nil) {
NSLog(@"Error: %@", [error localizedDescription]);
}
推荐答案
在插入新对象后保存mangedObjectContext。一旦我这样做，我得到的结果，我在寻找。
The problem was I needed to save the mangedObjectContext after inserting new objects. Once I did that I get the results I was looking for.
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