macOS app issues with sandboxing.

I'm developing an app to parse package.swift files.

When I run the following test code with "App Sandbox=NO" all works well. But I get the dreaded "xcrun: error: cannot be used within an App Sandbox" when "App Sandbox=YES". Fair enough.

So what I'm trying to do is to run "swift" inside my sandbox. To do this, I added the small "swift" command file into my Assets and in my project, and using that. However I still get the same error.

How can I run "swift" in my sandbox? or is there another way to parse package.swift files with "App Sandbox=YES"?

Code Block import SwiftUI
import Foundation
struct ContentView: View {
    var body: some View {
        Text("do the test").onAppear(perform: doTest)
    }
    
    func doTest() {
        if let swiftURL = Bundle.main.url(forResource: "swift", withExtension: nil) {
            let task = Process()
            task.executableURL = URL(fileURLWithPath: swiftURL.absoluteString)
            // path to my local .cachesDirectory, where I added a Package.swift file
            // e.g. FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)
            let arg3 = "/Users/......"
            task.arguments = ["package", "--package-path", arg3, "dump-package"]
            let pipe = Pipe()
            task.standardOutput = pipe
            do {
                try task.run()
            } catch (let error) {
                print("======> error \(error.localizedDescription)")
            }
            task.waitUntilExit()
            let data = pipe.fileHandleForReading.readDataToEndOfFile()
            print("---> data:  \(data)")
        }
    }
}

Code Block
import SwiftUI
import Foundation

struct ContentView: View {
var body: some View {
Text("do the test").onAppear(perform: doTest)
}

func doTest() {
if let swiftURL = Bundle.main.url(forResource: "swift", withExtension: nil) {
let task = Process()
task.executableURL = URL(fileURLWithPath: swiftURL.absoluteString)
// path to my local .cachesDirectory, where I added a Package.swift file
// e.g. FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)
let arg3 = "/Users/......"
task.arguments = ["package", "--package-path", arg3, "dump-package"]
let pipe = Pipe()
task.standardOutput = pipe
do {
try task.run()
} catch (let error) {
print("======> error \(error.localizedDescription)")
}
task.waitUntilExit()
let data = pipe.fileHandleForReading.readDataToEndOfFile()
print("---> data: \(data)")
}
}
}

Using Xcode 12.2 beta, macos 10.15.6 app.