- First, remove the current Xcode installation from your machine. You can probably skip this step but I wanted to start fresh. Plus — Xcode was behaving a little weird lately so this is a good opportunity to do that.
- Install Xcode 8 from the App Store. Make sure project files (.xcodeproj) and workspace files (.xcworkspace) can be opened with the new Xcode installation (remember to select the Later option whenever prompted).
- Download the Xcode 7.3.1 dmg file from Apple. Double-tap the newly downloaded dmg file in order to get the standard “Drag to install Xcode in your Applications folder”. Don’t do that. Instead, drag the Xcode icon to the desktop. Change the file name to Xcode 7.3.1. Now drag it to the Applications folder.
Now you have two versions of Xcode installed on your machine. Xcode 7.3.1 and Xcode 8.
Details: Install Xcode 7 & Xcode 8 side by side