Share video to facebook with FB SDK v4.16

ShareTool.m

@implementation ShareTool

+ (void)shareVideoToFacebookWithVideoURL:(NSURL *)videoAssetLibraryURL fromViewController:(UIViewController *)viewController {
    if (![[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"fb://"]]) {
        [ShareTool showAlertDialogWithTitle:@"NOTICE" andMessage:@"You Did Not Install Facebook" fromViewController:viewController];
        break;
    }

    FBSDKShareVideo *fbVideo = [[FBSDKShareVideo alloc] init];
    FBSDKShareVideoContent *fbVideoContent = [[FBSDKShareVideoContent alloc] init];
    fbVideo.videoURL = videoAssetLibraryURL;
    fbVideoContent.video = fbVideo;
    UIImage *previewImage = [UIImage imageNamed:@""];
    fbVideoContent.previewPhoto = [FBSDKSharePhoto photoWithImage:previewImage userGenerated:YES];

    FBSDKShareDialog *dialog = [[FBSDKShareDialog alloc] init];
    // default mode is FBSDKShareDialogModeAutomatic
    if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"fbauth2://"]]){
        dialog.mode = FBSDKShareDialogModeNative;
    } else {
        dialog.mode = FBSDKShareDialogModeBrowser;
    }
    dialog.shareContent = fbVideoContent;
    dialog.delegate = self;
    dialog.fromViewController = self;
    [dialog show];
}

+ (void)showAlertDialogWithTitle:(NSString *)title andMessage:(NSString *)message fromViewController:(UIViewController *)viewController {
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:[UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:nil]];
    [viewController presentViewController:alertController animated:YES completion:nil];
}

@end

不知道是怎么回事，分享事件有时候会失效，控制台打印"PBItemCollectionServicer connection disconnect"错误，Google之后并没有多少关于PBItemCollectionServicer这个关键词的结果，现在只知道这是一个iOS Runtime Service，到底哪里出了问题？