Problem is simple. Can't open this project because of permission issue. Take a look screenshot.
What I did before asking this question
Completely deleted Derived data folder using alias alias purgeallbuilds='rm -rf ~/Library/Developer/Xcode/DerivedData/*'
Changed Build settings > Change Compiler for C/C++/Objective-C to Default compiler.
Changed project folder's permissions for myself to read+write, and enclosed folders too.
Changed Standard architectures (armv7, arm64) and changed "Default Compiler (Apple LLVM 6.0)" compiler settings.
Using Xcode 7.0.1
Any other workarounds?