iosunity-game-enginebetaxcode16

Undefined symbols for architecture arm64: "__mh_execute_header" - Unity as a library embedding issue with Xcode 16 beta

Tried Xcode 16.1 beta today but project is not able to build because of the below error:

Undefined symbols for architecture arm64:
  "__mh_execute_header"

I am using unity as a lib in iOS project. And issue is with unity integration

 let machineHeader = UnsafeMutablePointer<MachHeader>.allocate(capacity: 1)
 machineHeader.pointee = _mh_execute_header
 ufw!.setExecuteHeader(machineHeader)

Did some research and found this solution by Apple DTS

Apple Forums

But not able to figure out how to solve. Any help is appreciated.

Solution

  • Fixed this issue using below code:

    let machineHeader = #dsohandle.assumingMemoryBound(to: MachHeader.self)
ufw!.setExecuteHeader(machineHeader)

    Explanation:

    While checking the answer from support team, I came across below line:

    In Swift you can use #dsohandle to get the start of the Mach-O image regardless of the image type, so this problem goes away. Well, you’ll need to combine that with an unsafeBitCast(_:to:).

    #dsohandle: This is a special Swift literal that gives you a handle to the dynamic shared object (DSO) that contains the current code. In other words, it provides access to the starting address of the Mach-O image (the binary that represents the executable or library).

    So replacing the direct reference to _mh_execute_header with a reference that uses #dsohandle help to solve the compilation error.

    Happy coding.