Xcode swift failed with exit code 254

Question

I am getting this compiler error in my code and I can\'t figure out why:

:0: error: unable to execute command: Segmentation fault: 11


        

Answer 1

I had this error and the bug was solved in Beta 7 available online today.

Answer 2

I'm getting the same error when adopt NSTextViewDelegate protocol for my class. If I remove that protocol, compilation goes fine. Strange indeed.

Answer 3

This is a Swift compiler bug, apparently testing for two or more implicitly unwrapped optionals causes the compiler to crash under some/many circumstances. Use Apple's Bugreporter to file this issue, mark it as duplicate of rdar://17212295.

Example

Here's a minimal example that crashes with the same error:

let a: String!
let b: String!

if a && b {
    println("have both")
}

Compile on command line as follows and witness the same crash:

$ xcrun swift -v -g crash.swift

Answer 4

In my case, i was calling an objective-c function from swift through bridge. Signature was like -

    - (SomeReturnType *)getSomething:(SomeOptions *)options
                          success:(void (^)(NSArray *response))success
                          failure:(void (^)(NSError *error))failure;

From swift, i was calling it as follows and getting compile error as "Xcode swift failed with exit code 254" -

    ObjCClass().getSomething(nil, success: {(response : Array!) in


        }, failure: {(error: NSError!)  in

        })

changing it to following worked for me -

     ObjCClass().getSomething(nil, success: {(response : [AnyObject]!) in


        }, failure: {(error: NSError!)  in

        })

Answer 5

I am getting this same error when I try to extend NSArray to have a foreach method:

extension NSArray {

    func foreach(f: (AnyObject -> ())) {
        for elem in self {
            f(elem)
        }
    }
}

It would appear that extending NSArray with func that takes a function argument will cause the same problems. I worked around the issue by defining a forEachInArray function that takes the NSArray as an argument:

func forEachInArray<T>(array: NSArray, f: (AnyObject -> ())) {
    for elem in array {
        f(elem)
    }
}

Answer 6

For the sake of providing other possible causes and how to fix them; I was trying to set the region of a map view within in dispatch block. If I commented out the setting of the region, the error goes away.

    dispatch_once(&centerMapLocation, {
//                var theSpan: MKCoordinateSpan = MKCoordinateSpanMake(0.01, 0.01)
//                var theRegion: MKCoordinateRegion = MKCoordinateRegionMake(manager.location.coordinate, theSpan)
//                self.map.setRegion(theRegion, animated: true)
                })
        }