RTMP AVPacket from NAL Units iOS

I'm writing video frames to a file (for hardware acceleration H264 encoding purpose) and reading the data from there while the writing is still happening. Long story short, I get the NALUs for every frame. My question is how to pass the NALUs to the AVPacket (FFmpeg's AVPacket) data parameter in order to send it over the network using the RTMP protocol.

What I do is append every NALU (on iOS, every frame is composed of 1 or two NALUs) and set it to the AVPacket data parameter, but it doesn't seem to work. Ideas? thanks.

I use this method to set the packet data: H264 Video Streaming over RTMP on iOS

from RTMP AVPacket from NAL Units iOS