向 NSObject 键添加值 - 表达式不可赋值

问：

我正在尝试将从 API 调用中返回的值添加到 Objective-C 中的对象。我在 Xcode 中收到一个错误，说“表达式不可分配”，不明白为什么。在我的中，我有一个带有值的对象，我正在尝试为 设置值。我在这种方法中做错了什么？carObjwarrantyPlannilwarrantyPlan

NSArray *carUUIDs = [carData valueForKeyPath:@"uuid"];
NSString *ownerUUID = ownerRecord[@"uuid"];
if (ownerID) {
    NSManagedObjectContext *context = [DataCenter viewContext];
    NSObject *carObj = [context objectsForEntityName:[CarObject entityName] matchingUUIDs:carUUIDs];
    
    for (id carID in carUUIDs){
        [WarrantyPlansService getWarrantyPlansForCarWithCarID:carID ownerID:ownerUUID completion:^(NSArray* response, NSError* error){
            //attach the response to the carData
            NSLog(@"%@", [carObj valueForKeyPath:@"warrantyPlans"]);
            [carObj valueForKeyPath:@"warrantyPlans"] = response;
        }];
    }