Merge videos & images in AVMutableComposition using AVMutableCompositionTrack, not AVVideoCompositionCoreAnimationTool?

Question

The code below exports a video using AVMutableComposition. But in the exported video, if you want an image to display for 3 seconds after the source video finis

Answer 1

After consulting others on SO and performing more web research, it seems like this is not possible. Merging an image with a video into a master video that is playable out of an app seems to require AVVideoCompositionCoreAnimationTool.