XCode 6.3.1 iOS project crashing on OS X 10.10.3

So, I just updated my OS X to 10.10.3 and XCode to 6.3.1.

Now, whenever I launch XCode the welcome screen works fine but every time I open/create a new iOS project it will crash. To be more precise, the workspace opens momentarily and the message "Loading PROJECT_NAME" is displayed on the top bar but soon after it crashes.

I tried changing the language but both Objective-C and Swift crashes.

Mac OS X projects are fine.

Swift playground (not iOS project) is also fine.

Tried XCode 6.4 beta and the same thing happens.

Here is the crash log: http://ift.tt/1JVU57E

What can I do to fix it? Thanks a lot!