This question comes around more and more often.

If for whatever reason you can't use your Mac to migrate the iOS SDK (for example: hard disk full, no space left to install Xcode), there are websites on which you can rent remote access to a Mac. Some of them offer free tryouts, enough for you to install Xcode and migrate the necessary files from there.

https://www.macincloud.com is one of them

https://www.virtualmacosx.com is another one

A Google search will probably give other alternatives...

The iOS SDK can't legally be redistributed by Apple's restriction (cf. Xcode EULA), so please don't ask around for someone to send you a compressed SDK archive. Thank you for your understanding.

P.S. I am not affiliated with any of the links above, I'm just forwarding information that I received from some users who found this workaround.