Command failed due to signal: Abort trap: 6

Question

Since Xcode 7 and Swift 2.0, I get the error above, like in the screenshot shown here:

Answer 1

Make sure you don't implement a private protocol into class extension. Most of the time would be quite strange to have a private protocol, but not necessary, depending on what you wish to encapsulate.

Something like, in the same file:

class C: ... {
}

extension C: P {
}

private protocol P: class {
}

Do this an you'll surely get Command failed due to signal: Abort trap: 6

Instead remove the private modifier from the protocol and the error is fixed.