I recently upgraded to new beta version of macOS 10.14 but after installing it when I tried to open my older version of Xcode 8.3.2, every time it gets crashed. Below is its
Xcode 8.X.X is doesn't support on macos 10.12 later version.
Cause of issue: "DYLD, [0x4] Symbol missing"
and also doesn't meet the swift version. so you need to upgrade your Xcode version or downgrade your os version below 10.12
Xcode 8's some versions is not compatible with macOS 10.14 just because of swift version. So, if you want XCode 8, did you try to upgrade first to 8.3 ?
As discussed in a few places like here and here, Xcode 8 does not run on Mojave. The best approach at this point is to either migrate your application to run with the latest Xcode, or run a VM with High Sierra or earlier that still supports your required version of Xcode.