How can I execute a shell script in Swift? - swift

Question

I am creating a macOS app with Swift that needs to download and run a shell script. I have been able to download the script with curl, but I can't run it. I am using a function from this answer to run other commands. When I use the App Sandbox in Xcode, I get the error /bin/bash: ./file.sh: Permission denied. When I try changing file permissions, I get the error chmod: Unable to change file mode on file.sh: Operation not permitted.
Here is my code:
func shell(_ command: String) -> String {
let task = Process()
task.launchPath = "/bin/bash"
task.arguments = ["-c", command]
let pipe = Pipe()
task.standardOutput = pipe
task.launch()
let data = pipe.fileHandleForReading.readDataToEndOfFile()
let output: String = NSString(data: data, encoding: String.Encoding.utf8.rawValue)! as String
return output
}
shell("curl https://www.example.com/file.sh -o file.sh")
shell("./file.sh")
Output:
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
1 16.0M 1 224k 0 0 231k 0 0:01:11 --:--:-- 0:01:11 231k
47 16.0M 47 7808k 0 0 4064k 0 0:00:04 0:00:01 0:00:03 4062k
100 16.0M 100 16.0M 0 0 6037k 0 0:00:02 0:00:02 --:--:-- 6037k
/bin/bash: ./file.sh: Permission denied