Using hackintosh (i7-4790K 4GHz, 16GB DDR3, GF980Ti) for developing on Xcode (both Swift and Objective-C) about an year, never get any errors. But now I need to use Instruments
The signing fix in the most-liked answer unfortunately impedes the execution rights of Instruments, so while it's then visible, the time profiler will not work.
Fortunately the iBooks thread from the other answer is not over yet, and the suggested (and provided) solution is to use a kernel extension that makes Nvidia drivers appear validated.
https://github.com/mologie/NVWebDriverLibValFix
This basically solves the problem at its root and is the next best thing to having Nvidia drivers actually signed by Apple.
With 10.13 / High Sierra the Web-Driver should work without any hack / modification (it should be removed when updating)