Why AVPlayer ask several union range in same session?

问题

I'm would to know why AVPlayer ask's union ranges in requests. Example: 1. We have good wi-fi connection. 2. Track with total length = 1000000.

AVPlayer in first will ask bytes=0-1 - its ok, it just "ping" the availability of track.

But after that it will ask bytes=0-999999 - and get content-len 1000000;

And after that it will ask bytes=40000-999999 - and get content-len 599999;

Why it make third request if we must have all data from second request (bytes=0-999999)?

来源：https://stackoverflow.com/questions/18058011/why-avplayer-ask-several-union-range-in-same-session