Hi...I'm going to add this as a bug as I'm pretty sure it is not the intended behaviour.
When on the iPhone app, after performing a search (be it inside a playlist or the general search) there is no way to swipe on a track and perform the secondary actions. This is very frustrating for queuing songs and creating the "Now Playing" playlist, as the track can only be played "Now" and not queued.
I hope this explanation was clear, please let me know if there's more information needed. Also, please help me bring this into the attention of Spotify Staff.
We're working on solving this issue, meanwhile, there's a workaround to get the "context menu" on tracks you've searched for.
After you performed your search and it doesn't work to swipe for the context menu, hide the search view and navigate somewhere else, and then go back, and it should be able to swipe for the context menu again.