AFNetworking 上传到node失败，node读不到files？

Question

用web page 上传图片的时候，在node中可以看到
console.log(req.files):

但是在iOS中使用 AFNetworking 上传图片，node读不出来：

iOS的代码如下：

    NSString *urlString = [baseUrlString stringByAppendingString:@"account/avatar"];
    
    NSDictionary *parameters = @{@"token": self.token};
    NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:urlString parameters:parameters constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
        [formData appendPartWithFileURL:filePath name:@"file" fileName:@"filename.jpg" mimeType:@"image/jpeg" error:nil];
    } error:nil];
    
        [request setValue:self.token forHTTPHeaderField:@"token"];
    
    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
    
    NSURLSessionUploadTask *uploadTask;
//    uploadTask = [manager
//                  uploadTaskWithStreamedRequest:request
//                  progress:nil completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
//                      if (error) {
//                          NSLog(@"Error: %@", error);
//                      } else {
//                          NSLog(@"%@ %@", response, responseObject);
//                      }
//                  }];
//    
    
    uploadTask = [manager uploadTaskWithRequest:request fromData:[NSData dataWithContentsOfURL:filePath] progress:nil completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
                              if (error) {
                                  NSLog(@"Error: %@", error);
                              } else {
                                  NSLog(@"%@ %@", response, responseObject);
                              }
    }];
    
    [uploadTask resume];