How to upload results to label in shell from swift code?

Question

Everything is working fine, but I don't understand why the wrong label "loading" doesn't update the percentage. while i print the output value is continuously changing

                        do {
                        @discardableResult
                          func shell(_ args: String...) -> (String?, Int32) {
                          let task = Process()
                          task.launchPath = "/usr/bin/env"
                          task.arguments = args
                          let pipe = Pipe()
                          task.standardOutput = pipe
                          task.standardError = pipe
                          task.launch()
                          let data = pipe.fileHandleForReading.readDataToEndOfFile()
                          let output = String(data: data, encoding: .utf8)
                          task.waitUntilExit()
                          return (output, task.terminationStatus)
                        }
             shell(....)
             let strURL = "http://download.com/load.zip"
             let url = URL(string: strURL)
             FileDownloader(url! as NSObject).download(url: url!)

             var result = ""
             func checkdl() {

             let dir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first
             let fileURL = dir!.appendingPathComponent("load.txt")
             result = try! String(contentsOf: fileURL, encoding: .utf8)

             print(result)
             if result.contains("100.0") {
             try! "".write(to: fileURL, atomically: true, encoding: String.Encoding.utf8)
             print("download done")

             } else {

              sleep(2)
             loading.stringValue = result+"%"
              checkdl()

              }
           }
        checkdl()

       shell(....)
   }

Everything is working fine, but I don't understand why the wrong label "loading" doesn't update the percentage. while i print the output value is continuously changing