A macOS privileged helper tool that uses SubProcess crashes on intel Macs (running macOS 13 - 15: unable to test on macOS 26 on intel) with the error that libswiftCompatibilitySpan.dylib cannot be loaded when built with XCode 26.3. The same helper tool works as expected with XCode 26.2.
The helper is installed using SMAppService.
When I remove the dependency for SubProcess, the crash no longer occurs (but important functionality is also disabled).
The helper is installed using SMAppService.
Is it using the BundleProgram property, so that the system runs the privileged helper tool from within the app bundle?
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—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
Yes, it's using the BundleProgram property.
OK.
When you run this command, what do you see:
% find YourApp.app -name "libswiftCompatibilitySpan.dylib"
YourApp.app/Contents/Frameworks/libswiftCompatibilitySpan.dylib
libswiftCompatibilitySpan.dylib exists to provide Span support on older systems. AFAICT it’s expected to work on Intel Macs running 13.1 or later:
% vtool -show-build Test817488.app/Contents/Frameworks/libswiftCompatibilitySpan.dylib
Test817488.app/Contents/Frameworks/libswiftCompatibilitySpan.dylib (architecture x86_64):
Load command 10
cmd LC_BUILD_VERSION
cmdsize 32
platform MACOS
minos 13.1
sdk 26.2
ntools 1
tool LD
version 1230.1
…
And I tested it here in my office, on both 26.2 (Rosetta) and 13.6.1 (real hardware), and I didn’t have a problem. However, that was from my main app, not from a privileged helper tool, so it’s possible that there’s something specific to privileged helper tools in play here.
My test code is pasted in at the end of this email. If you temporarily add this to your app, does it work on the same Intel Mac?
And with that in place, does your helper tool spontaneously start working?
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—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
func runTest() {
print("AppDelegate.testAction(_:)")
Task {
do {
print("will list")
let result = try await run(.name("ls"), output: .string(limit: 4096))
print("did list, \(result)")
} catch {
print("did not list, \(error)")
}
}
}
The find command returns nothing when the app is built with XCode 26.3 or XCode 26.2.
Is there a build setting that ensures that libswiftCompatibilitySpan.dylib gets included? I've tried copying it in build phases, but that crashes the main app.
I do have "Always Embed Swift Standard Libraries" set to yes in the main app.
Including the sample code in the helper (NB: the helper tool doesn't have an app delegate - it's a command line tool) also doesn't resolve the crash.
If it's helpful, here's the relevant piece of the crash log from the helper:
Termination Reason: Namespace DYLD, Code 1 Library missing
Library not loaded: @rpath/libswiftCompatibilitySpan.dylib
Referenced from: <91AD8720-25FD-3ABB-B10A-6A7630E7BA48> /Users/USER/Library/Developer/Xcode/DerivedData/MyApp-hapnwyzmnoqmoybwzlybjoupeflc/Build/Products/Debug/MyApp.app/Contents/MacOS/com.micromat.TTDaemon
Reason: tried: '/usr/lib/swift/libswiftCompatibilitySpan.dylib' (no such file, not in dyld cache), '/System/Volumes/Preboot/Cryptexes/OS/usr/lib/swift/libswiftCompatibilitySpan.dylib' (no such file), '/Users/myUser/Library/Developer/Xcode/DerivedData/MyApp-hapnwyzmnoqmoybwzlybjoupeflc/Build/Products/Debug/PackageFrameworks/libswiftCompatibilitySpan.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/Users/myUser/Library/Developer/Xcode/DerivedData/MyApp-hapnwyzmnoqmoybwzlybjoupeflc/Build/Products/Debug/PackageFrameworks/libswiftCompatibilitySpan.dylib' (no such file), '/Users/myUser/Library/Developer/Xcode/DerivedData/MyApp-hapnwyzmnoqmoybwzlybjoupeflc/Build/Products/Debug/MyApp.app/Contents/Fra
(terminated at launch; ignore backtrace)
Including the sample code in the helper
Ah, I think you misunderstood that test. I was suggesting that you temporarily add that code to the app, with some sort of debug UI wired up to call it. That has two benefits:
libswiftCompatibilitySpan.dylib which might then ‘fix’ your helper tool.And if that second point is true, it confirms the nature of the problem and suggests a path to a workaround.
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"