How can I set the paper size with SWIFT / iOS, so my thermal printer airprints more than 140mm

Question

I have made an app, and the app needs to print a receipt. I have a star TSP650 II thermal printer that supports AirPrint. I can print and that works fine. The use of previous selected printer also works fine.

However, it cuts automatically after 140mm, and sometime my receipts can get 2 or 3 timers longer.

How can I programmatically set the paper length ?

    func SelecteDefaultPrinter(){
        let printerPicker = UIPrinterPickerController(initiallySelectedPrinter: nil)
        printerPicker.present(from: CGRect(x: 0, y: -100, width: 600, height: 500), in: self.view, animated: true) { (printerPicker, userDidSelect, error) in
            if userDidSelect {
                //Here get the selected UIPrinter
                self.defaultPrinter = printerPicker.selectedPrinter!
                let js="storeprinter('\(printerPicker.selectedPrinter!.displayName)','\(printerPicker.selectedPrinter!.url)');"
                self.webView.evaluateJavaScript(js, completionHandler: nil)
                self.printerURL = printerPicker.selectedPrinter!.url
                self.user!.printerurl = printerPicker.selectedPrinter!.url.absoluteString
                print(self.user!)
                //   self.printText()
            }
        }
    }

    func printText() {
        let printInfo = UIPrintInfo(dictionary:nil)
        printInfo.outputType = UIPrintInfo.OutputType.general
        printInfo.jobName = "print Job"
        printController.printInfo = printInfo
        let formatter = UIMarkupTextPrintFormatter(markupText: html)
        formatter.perPageContentInsets = UIEdgeInsets(top: 2, left: 5, bottom: 0, right: 5)

        printController.printFormatter = formatter

        if(printerURL  ==  URL(string: "http://notset.local")) {
            print("no printer selected");
            printController.present(animated: true, completionHandler: nil)
        } else {
            let currentPrinter = UIPrinter(url: printerURL!)

            printController.print(to: currentPrinter, completionHandler: {(controller, success, error) -> Void in
                if success {
                    debugPrint("Printing Completed.")
                } else {
                    debugPrint("Printing Failed.")
                }
            })
        }  
    }

I am fairly new to the whole iOS / SWIFT, so please help.