Xamairn.Forms iOS: Switching tabs would make the player black .

## 🐛 Bug Report

I have an app with multiple tabs one of them has the VideoView that plays the sample video automatically , when i switch to the next tab i can still hear the video playing . However, when i switch back to the video tab , the video is still playing (i can hear it) but I can see only black box instead of the actual video .

I think it has to do with what this link says
https://stackoverflow.com/questions/21737017/avplayerlayer-blank-after-entering-background-while-being-in-a-hidden-controller/42822384#42822384

**Note:** This works on Android

### Expected behavior
You can see the video when you switch back between the tabs

### Reproduction steps
I have uploaded a sample project.
### Configuration

**Version:** 0.8.9
[MediaManagerSample.zip](https://github.com/martijn00/XamarinMediaManager/files/3637390/MediaManagerSample.zip)

**Platform:**
- [x] :iphone: iOS
- [ ] :robot: Android
- [ ] :checkered_flag: WPF
- [ ] :earth_americas: UWP
- [ ] :apple: MacOS
- [ ] :tv: tvOS
- [x] :monkey: Xamarin.Forms