Question: Most iOS version are downloaded, but all ios Version (iOS 8.x, iOS 9.x, etc doesn't appear in the dropdown on Xcode.  

How to reset this? (I know I can re-add manually using "Devices, Add", but i'm sure it's a way to just reset all, and have Xcode to offer redownload the sim.)

EDIT: The iOS I need to redownload, are the one that are ALREADY downloaded. – Franck 

[![enter image description here](https://i.stack.imgur.com/HSgpw.png)](https://i.stack.imgur.com/HSgpw.png)

[![enter image description here](https://i.stack.imgur.com/DQ40T.png)](https://i.stack.imgur.com/DQ40T.png)

Answer: 
I get my answer from the 'snapshot' git. (Fastlane)

> 
> reset\_simulators is removing all simulators and create new one only
>  for the latest iOS version. If you want to recreate simulators for
>  other versions you have to provide the list of the versions after the
>  --ios argument, e.g.
> 
> 
> snapshot reset\_simulators --ios 8.3,8.4,9.0,9.1
> 
> 
> 

Work perfectly!
Click here to restart download ...
[![enter image description here](https://i.stack.imgur.com/d1He3.png)](https://i.stack.imgur.com/d1He3.png)

But if you really want to re-download, you can just delete the simulators and Xcode will offer to re-download.  

Go to `/Library/Developer/CoreSimulator/Profiles/Runtimes` and delete the files/bundles there