Apple Watch : will the App on iPhone run in the background

Am trying a simple Apple Watch App. the question I have is : will the iPhone App be able to run always in the background? In the App, I want to fetch some files from a server & store them in the iPhone (I want to do this everyday at a specific time), so that when the user opens the Apple Watch App, the file can be showed immediately (and no need to wait for it be downloaded then).