Question

我正在按照apple：（https://developer.apple.com/library/ios/documentation/DataManagement/Conceptual/CoreDataSnippets/Articles/fetchExpressions.html）的例子来获取不同的＆＃34;值＆＃34;

NSEntityDescription *ahrsMessage = [NSEntityDescription entityForName:@"AHRSMessage" inManagedObjectContext:self.managedObjectContext];
    NSFetchRequest *distinctFetch = [NSFetchRequest new];
    [distinctFetch setEntity:ahrsMessage];
    [distinctFetch setResultType:NSDictionaryResultType];
    [distinctFetch setReturnsDistinctResults:YES];
    [distinctFetch setPropertiesToFetch:@[@"flightRecordings"]];

    NSError *e = nil;
    id requestedValue = nil;
    NSArray *objects = [self.managedObjectContext executeFetchRequest:distinctFetch error:&e];
    if (objects == nil) {
        NSLog(@"ERROR");
    }


    for (NSDictionary *dict in objects) {
        NSLog(@"dict: %@", dict);

       [dict objectForKey:@"flightRecordings"];

    }

当我在调试器中探索值objects[1]时，我看到我的密钥为_PFEncodedString *，我的值为_NSCoreDataTaggedObjectID *我不清楚的是如何实际获取我的CoreData对象退出此数据类型。

Answer 1

我刚看到这篇文章，自己寻找答案。因此，如果有人遇到此问题，您可以通过在NSManagedObjectContext的 objectWithID：方法中传递结果字典中的值来获取实际的 NSManagedObject 。

这就是：

NSManagedObjectID *managedObjectID = [dict objectForKey:@"fetched_property_name"]
NSManagedObject *managedObject = [moc objectWithID:managedObjectID]

如何从_NSCoreDataTaggedObjectID获取对象或值

1 个答案: