FBSDKGraphRequestConnection requestConnectionDidFinishLoading从未调用

Question

我试图批量调用Open Graph。 这是我的代码：

FBSDKGraphRequestConnection * connection = [[FBSDKGraphRequestConnection alloc] init];
for (NSString * userID in userIDArray) {

     FBSDKGraphRequest * request = [[FBSDKGraphRequest alloc] initWithGraphPath:userID parameters:nil];

     [connection addRequest:request completionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) {

         if (!error) {
               NSLog(@"%@ added", friend);
         }
         else {
               NSLog(@"error when fetching friend's detail:%@", error);
         }

     }];

}

connection.delegate = self;
[connection start];

我已经向协议确认了我的课程：

@interface MYClass : NSObject <FBSDKGraphRequestConnectionDelegate>

在我的.m我已经实现了委托方法：

- (void)requestConnectionDidFinishLoading:(FBSDKGraphRequestConnection *)connection {
    NSLog(@"requestConnectionDidFinishLoading");
}

- (void)requestConnectionWillBeginLoading:(FBSDKGraphRequestConnection *)connection {
    NSLog(@"requestConnectionWillBeginLoading");
}

- (void)requestConnection:(FBSDKGraphRequestConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"didFailWithError");
}

即使所有请求都已完成，也永远不会调用委托方法requestConnectionDidFinishLoading，而其他两个工作正常。

任何人有同样的问题吗？