ios - Core Data iOS 中完全匹配的 NSString

Question

我在 CoreData 中拥有名为 myentity 的实体和名为 myuniqueid 的属性，并且我想运行 SQL 查询，如下所示:

Select * from myentity where myuniqueid == 1000

如何获取与 SQL 查询中匹配的指定行？这样我想过滤 myuniqueid 为 1000 的所有行。

我的代码:

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSManagedObjectContext *context = [self managedObjectContext];
    if (context == nil) {}
    else {
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"myentity" inManagedObjectContext:context];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"myuniqueid == 1000"];
    [fetchRequest setPredicate:predicate];

    [fetchRequest setEntity:entity];
    NSArray *items = [context executeFetchRequest:fetchRequest error:nil];
        for (int i=0; i<4; i++) {
            NSManagedObject *mo = [items objectAtIndex:i];  // assuming that array is not empty
            id value = [mo valueForKey:@"myuniqueid"];
            NSLog(@"SENDER: %@",value);
        }

    }

我收到错误:“无法为谓词生成 SQL (myuniqueid == 1000)(RHS 上有问题)”

Answer 1

试试这个谓词:

NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"myentity"];
fetchRequest.predicate = [NSPredicate predicateWithFormat:@"myuniqueid == %@", @(1000)];
NSArray *items = [[self managedObjectContext] executeFetchRequest:request error:nil];