Cannot handle projects from Xcode 16.3

[fruitcoder]

The Xcode 16.3 project structure changes the shellScript of a build phase to an Array instead of string. Sample diff

- shellScript = "sh ../../scripts/swiftlint.sh\n";
+ shellScript = (
+  "sh ../../scripts/swiftlint.sh",
+  "",
+ ); 

This results in the error: [Xcodeproj] Type checking error: got Array for attribute: attribute 'shellScript' (type: simple, classes: [String], owner class : PBXShellScriptBuildPhase

I haven't found any project-specific conditionals for declarations so I'm unsure what's the best (backwards compatible) way to solve this but the relevant line is here.

Can someone point me in the right direction how I could fix this then I'd open a PR.

[keatalay]

hit this on a Flutter app + CocoaPods trying to add a watchOS App target, and it turns into a hard catch-22 between Xcode's target wizard and pod install. Env: Xcode 26.5 / macOS 26.3.1, CocoaPods 1.16.2 (Xcodeproj 1.27.0).

• Adding the target via File ▸ New ▸ Target ▸ watchOS ▸ App crashes Xcode itself on Finish (NSInvalidArgumentException in -[Xcode3ProjectTemplateFactory projectForProjectPath:context:]) unless the project is already on the new objectVersion-77 / synchronized-folder format.
• Upgrading the project format to satisfy the wizard is exactly what produces the Array-form shellScript, so pod install then dies with got Array for attribute shellScript (… owner class: PBXShellScriptBuildPhase) — this issue.
• Setting the format to "Xcode 16.0" restores pod install, but that format isn't new enough for the watch-target wizard, which still crashes.

So there's no project format under which both pod install and the watchOS-target wizard succeed:

Project format	pod install	Add watchOS target
objectVersion 54 (Flutter default)	✅	❌ Xcode crash
Xcode 16.0	✅	❌ Xcode crash
latest / objectVersion 77 (Array shellScript)	❌ this issue	✅

(Control: the same wizard works fine in a brand-new empty Xcode project, which is born at objectVersion 77 — so it's specifically the CocoaPods-integrated, older-format project that's stuck.) Xcodeproj accepting the Array form of shellScript would unblock it: the project could sit at the format the wizard needs while keeping pod install working. Happy to share a minimal repro