Swift 2.1 OSx shell commands using NSTask work when run from xcode, but not when exported

Question

I wrote a simple OSx (10.11) application to execute shell commands when a button is pressed. It works when I run it from xcode, but when I export the application via \"archive\"

Answer 1

Your issue is the result of two things happening together:

• you return default values

• you don't specify alternative branches for the control flow

What happens is that it hides potential failures, and leads to code that is very hard to debug, as you experienced.

A possible solution with your existing code is to cover all possible ways, meaning providing else branches to your if var string = String.fromCString(UnsafePointer(errdata.bytes)) conditions, where you will handle errors.

Answer 2

Thanks to Eric D. I simplified my code and now everything is working.

func runCommand(path : String, args : [String]) -> (output: NSString, error: NSString, exitCode: Int32) {
    let task = NSTask()
    task.launchPath = path
    task.arguments = args

    let outpipe = NSPipe()
    task.standardOutput = outpipe
    let errpipe = NSPipe()
    task.standardError = errpipe

    task.launch()

    let outdata = outpipe.fileHandleForReading.readDataToEndOfFile()
    let output = NSString(data: outdata, encoding:  NSUTF8StringEncoding)

    let errdata = errpipe.fileHandleForReading.readDataToEndOfFile()
    let error_output = NSString(data: errdata, encoding: NSUTF8StringEncoding)

    task.waitUntilExit()
    let status = task.terminationStatus

    return (output!, error_output!, status)
}