I just purchased an Apple TV 4K to use with my iPhone 6s plus after my Chromecast broke. I just noticed that when casting movies to my tv using Airplay, I cannot close the app doing the casting. For example, the Hulu app on my phone, which supports Airplay, will let me switch to a different app while casting a movie. However, as soon as I quit the Hulu app (i.e. double press the home button and swipe up), Apple TV will no longer play the movie. This is very different from Chromecast because after casting the movie to Chromecast, it is the Chromecast that does the job of pulling the movie from its internet source, and I can freely quit the app without affecting the casting. In fact, when casting Hulu movies through chrome cast in the past, I could quit the Hulu app and the movie would still be playing.
I understand that there is no need to quit iPhone apps, but that's not the point here.
My questions are:
Does Apple TV, while performing Airplay, do the job of pulling the movies from the internet by itself, or does my iPhone have to do all the heavy lifting?
If Apple TV can get the movies from the internet sources, why do the apps on my iPhone have to stay active?
Is there a way to quit apps on my iPhone without affecting Airplay?