Running from Xcode 6.1 - Linker errors

Question

I am building a SpriteKit game using the Xcode 6.1 beta which I originally created using the release version of Xcode 6.0.1. I switched to 6.1 because of the corrupted sks problems in 6.0.1. Now, I am getting a runtime error on launch:

dyld: Symbol not found: _swift_isaMask

I understand that this is a linker error, but what should I do to fix it? Or should I just create a new project in Xcode 6.1 and copy over my files? Thank you.

EDIT 1: I tried creating a completely new project using Xcode 6.1, and I'm still getting the same error.

Answer 1

I had the same problem; I have cleaned my project (cmd+shift+k) and this fixed the bug.

Answer 2

Cleaning and re-building the project did not help me. In my case, I had a class which was a simple UIViewController, implementing a datasource and delegate at the same time:

   public class MyViewController: UIViewController, UIPickerViewDelegate,
                    UIPickerViewDataSource {
      ...

When I removed the two protocols (UIPickerViewDelegate and UIPickerViewDataSource) and removed all methods from the class which implemented them, then I could build without an issue. I then re-added the methods only, it built, then went back to what I had before and - get this - it built. Ugh.

So there seems to be some issues with the Swift linker. Play around with the class in question, simplifying it until it builds, then add piece by piece back.