EXC_BAD_ACCESS KERN_INVALID_ADDRESS crash

Question

My app has been running fine in debugging mode through Xcode, but whenever it's downloaded through TestFlight, it crashes with this error: EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x000200013f7b9e78.

It's crashing at this line. I see specialized Array.withUnsafeMutableBufferPoint in this stack trace that it's probably related to.

self.array.sortInPlace. {
                (($0 as Dictionary<String, AnyObject>)["time"] as? String) > (($1 as Dictionary<String, AnyObject>)["time"] as? String)
            }

In Swift 1.3 I was using sort, and now in Swift 2 I'm using sortInPlace. Not sure if this makes a difference, but I do know that the result of sort isn't called because it's immutable.

Thread : Crashed: com.apple.main-thread
    0  libswiftCore.dylib             4302688056 _swift_retain_(swift::HeapObject*) + 8
    1  App                          4295962040 specialized LiveFeedViewController.(viewDidLoad(LiveFeedViewController) -> () -> ()).(closure #3).(closure #1) (LiveFeedViewController.swift)
    2  App                          4295785356 specialized thunk (LiveFeedViewController.swift)
    3  App                          4295953880 specialized _siftDown<A where ...> (inout A, A.Index, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool) -> () (LiveFeedViewController.swift)
    4  App                          4295952448 specialized _heapSort<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool) -> () (LiveFeedViewController.swift)
    5  App                          4295938144 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    6  App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    7  App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    8  App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    9  App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    10 App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    11 App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    12 App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    13 App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    14 App                          4295938120 specialized _introSortImpl<A where ...> (inout A, Range<A.Index>, inout (A.Generator.Element, A.Generator.Element) -> Bool, Int) -> () (LiveFeedViewController.swift)
    15 App                          4295960640 specialized specialized MutableCollectionType<A where ...>.sortInPlace<A where ...>((A.Generator.Element, A.Generator.Element) -> Bool) -> () (LiveFeedViewController.swift)
    16 App                          4295730388 _TPA__TTSg5GSaGVSs10DictionarySSPSs9AnyObject___GSaGS_SSPS0____Ss21MutableCollectionTypeSs_GVSs17IndexingGeneratorGSaGS_SSPS0_____GS2_GSaGS_SSPS0_____Ss13GeneratorTypeSs_GS_SSPS0____SiSiSs21RandomAccessIndexTypeSs_SiSiSs18_SignedIntegerTypeSs_SiSiSs33_BuiltinIntegerLiteralConvertibleSs_SiSiSs16SignedNumberTypeSs_SiSiS6_Ss_Si_GVSs10ArraySliceGS_SSPS0____GS8_GS_SSPS0____Ss9IndexableSsGS8_GS_SSPS0____Ss12SequenceTypeSs_GS2_GS8_GS_SSPS0_____GS2_GS8_GS_SSPS0_____S3_Ss_GS_SSPS0____SiSiSs16ForwardIndexTypeSs_SiSiS5_Ss_SiSiS6_Ss_Si_GS8_GS_SSPS0_____GS_SSPS0____GS_SSPS0______TFFeRq_Ss21MutableCollectionTypeqq_Ss16MutableIndexable5IndexSs21RandomAccessIndexType_SsS_11sortInPlaceuRq_S_qq_S0_5IndexS1__FRq_FFTqqq_Ss14CollectionType9GeneratorSs13GeneratorType7Elementqqq_S2_9GeneratorS3_7Element_SbT_U_FTGVSs20UnsafeMutablePointerQQQPS_9Generator7Element_Si_T_ (LiveFeedViewController.swift)
    17 App                          4295730548 _TPA__TTSg5GSaGVSs10DictionarySSPSs9AnyObject___GSaGS_SSPS0____Ss21MutableCollectionTypeSs_GVSs17IndexingGeneratorGSaGS_SSPS0_____GS2_GSaGS_SSPS0_____Ss13GeneratorTypeSs_GS_SSPS0____SiSiSs21RandomAccessIndexTypeSs_SiSiSs18_SignedIntegerTypeSs_SiSiSs33_BuiltinIntegerLiteralConvertibleSs_SiSiSs16SignedNumberTypeSs_SiSiS6_Ss_Si_GVSs10ArraySliceGS_SSPS0____GS8_GS_SSPS0____Ss9IndexableSsGS8_GS_SSPS0____Ss12SequenceTypeSs_GS2_GS8_GS_SSPS0_____GS2_GS8_GS_SSPS0_____S3_Ss_GS_SSPS0____SiSiSs16ForwardIndexTypeSs_SiSiS5_Ss_SiSiS6_Ss_Si_GS8_GS_SSPS0_____GS_SSPS0____GS_SSPS0______TTRGRq_Ss21MutableCollectionTypeqq_Ss16MutableIndexable5IndexSs21RandomAccessIndexType_XFo_dGVSs20UnsafeMutablePointerqqq_Ss14CollectionType9GeneratorSs13GeneratorType7Element_dSi_dT_zoPSs9ErrorType__XFo_dGS2_qqq_S3_9GeneratorS4_7Element_dSi_iT_zoPS5___ (LiveFeedViewController.swift)
    18 App                          4295730716 _TPA__TTSg5GVSs10DictionarySSPSs9AnyObject___T____TFFSa42_withUnsafeMutableBufferPointerIfSupportedu__rFRGSaq__FzFzTGVSs20UnsafeMutablePointerq__Si_qd__GSqqd___U_FzRGVSs26UnsafeMutableBufferPointerQd___Q_ (LiveFeedViewController.swift)
    19 App                          4295954668 specialized Array.withUnsafeMutableBufferPointer<A><B>((inout UnsafeMutableBufferPointer<A>) throws -> B) throws -> B (LiveFeedViewController.swift)
    20 App                          4295959880 specialized specialized MutableCollectionType<A where ...>.sortInPlace<A where ...>((A.Generator.Element, A.Generator.Element) -> Bool) -> () (LiveFeedViewController.swift)
    21 App                          4295895596 LiveFeedViewController.(viewDidLoad(LiveFeedViewController) -> () -> ()).(closure #3) (LiveFeedViewController.swift:1862)
    22 libdispatch.dylib              6875551464 _dispatch_call_block_and_release + 24
    23 libdispatch.dylib              6875551400 _dispatch_client_callout + 16
    24 libdispatch.dylib              6875573680 _dispatch_main_queue_callback_4CF + 1844
    25 CoreFoundation                 6518931960 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12
    26 CoreFoundation                 6518923360 __CFRunLoopRun + 1628
    27 CoreFoundation                 6518066336 CFRunLoopRunSpecific + 384
    28 GraphicsServices               6704955528 GSEventRunModal + 180
    29 UIKit                          6609391612 UIApplicationMain + 204
    30 App                          4296344512 main (AppDelegate.swift:23)
    31 libdyld.dylib                  6875752632 start + 4

UPDATE:

This is all in Swift 2, and the array is an array of dictionaries, declared as var array = [[String:AnyObject]](). It's populated by appending a series of dictionaries, like this.

self.dict["foo"] = 0
self.dict["bar"] = "dog"
self.array.append(self.dict)

My concern is that its within a dispatch_group_notify; it's waiting on series of dispatch_group_leaves. Could that have something to do with it? That looks like this:

dispatch_group_notify(group, queue) { () -> Void in

      self.array.sortInPlace {
          (($0["foo"] as? Int) > (($1 )["foo"] as? Int))
      }
}

Answer 1

I'm getting the same issue but it only affects ~50% of devices, and only those running the release version of the app. My code is not using anything like dispatch_group.

In my case I was using code such as:

contacts.sortInPlace({ $0.name.localizedCaseInsensitiveCompare($1.name) == .OrderedAscending })

It was fixed when I replaced it with:

contacts = contacts.sort({ $0.name.localizedCaseInsensitiveCompare($1.name) == .OrderedAscending })

Since it only affects a limited amount of users, crashes in a low level Swift API, and is fixed by replacing with sort, I believe this is a bug in Apple's code.

I recommend filing a bug with Apple and using sort in the meantime.

Note: Another similarity between your code and mine is the usage of shorthand argument names (i.e. $0 and $1). However, even if I replace those with named arguments, it still crashes.

Update: Many people are experiencing the same issue on the apple forums. It seems to be fixed in the latest Xcode beta according to that thread.