Xcode 9 is a major improvement. They rewrote the editor which is now blazing fast and introduced (and open sourced as part of LLVM!) a new refactoring engine ca

Xcode 9 is a major improvement. They rewrote the editor which is now blazing fast and introduced (and open sourced as part of LLVM!) a new refactoring engine capable of refactoring C, C++, Objective C and Swift. Also, they are currently in the process of rewriting the build system, with a preview shipping with Xcode 9.