I know this question is a duplicate and the permanent solution is to update Xcode to the latest version available.
What I'm looking for is only the developer disk image of every iOS version updates. Developer disk image of every version is less than 15 MB compared to the 4 GB+ download size of Xcode app/.dmg/.xip file.
Stackoverflow is maintaining a thread for links to every version of Xcode.dmg files. How to download Xcode DMG or XIP file?
If I have only the developer disk image, I can run my projects after every iOS updates without re-downloading the entire Xcode or being forced to update the Mac OS version.
Though I acknowledge that running on the latest version of Xcode and Mac OSX is the best practice, sometimes it can also be a problem. Especially if you have slow download speeds and not so reliable Apple download servers with terrible resume support.
My current scenario is something like that. I'm running on 10.11.6 El Capitan and Xcode 8.2. Yesterday I have updated my iPhone 6 to iOS 10.3.1. Now I have to update the Xcode to 8.3 else I won't be able to run my projects on my device. But to download Xcode 8.3 from Appstore my OSX version should be MacOS Sierra.
My project won't run on simulator due to the SDK's I'm using and now I'm stuck with downloading MacOS Sierra first (5-6 GB) and then Xcode 8.3 (4-4.5 GB) on frustrating 1 Mb/s connection. All of this for a 15 MB file.!
What I want to know is, is there any source or thread in SO that shares these developer disk images and how secure it is to use it (Can this image be tampered?). I don't know whether Apple will provide this option. And I'm equally aware that downloading dev tools from non-trusted sources can get your hands burned (like the developers from China who downloaded modified versions of Xcode outside AppStore or developer.apple.com and got malware in their apps)