ios - 从 Url 创建工作 UIPrinter 对象以进行无对话打印

Question

场景:引导模式锁定应用程序接受一些用户输入(姓名等)并打印出一张票。用户无法选择打印机。

我计划的解决方案是保存我拥有的打印机 URL，其形式为:

ipp://<hostname>.local.:5001/<printername>

从这个存储的字符串构建 UIPrinter 对象:

var printerURL = NSUrl.FromString(SettingsService.OptPrinterUrl);
var printer = UIPrinter.FromUrl(printerURL);

然后我调用:

printer.ContactPrinter((available) => {
        if (available) {
            //
        }
    });

或

var printInterface = UIPrintInteractionController.SharedPrintController;
printInterface.PrintToPrinter(printer, (handler, completed, error) =>
                                {
                                    if (!completed && error != null) {
                                        UIAlertView alert = new UIAlertView("Guest Check-In App", "Print Error", null, "Ok", null);
                                        alert.Show();
                                    }
                                });

没有阳性结果。

但是，当使用从 UIPrinterPickerController 返回的 UIPrinter 对象(如下所示)时，一切正常。

var printerPicker = UIPrinterPickerController.FromPrinter(null);
printerPicker.PresentFromRect(new CGRect(0,0,100,100),this.View,true, delegate(UIPrinterPickerController handler, bool completed, NSError error) {
            printer = printerPicker.SelectedPrinter;
        });

我只能创建一个有效的 UIPrinter 对象，而不能像这样直接使用 UIPrinterPickerController 中的对象:

var printerPicker = UIPrinterPickerController.FromPrinter(null);
                        printerPicker.PresentFromRect(new CGRect(0,0,100,100),this.View,true, delegate(UIPrinterPickerController handler, bool completed, NSError error) {
                            printerPickerPrinter = printerPicker.SelectedPrinter;
                        });
var printer = (UIPrinter)UIPrinter.FromObject(printerPickerPrinter);

总结我需要的是一种“记住”打印机并使用该打印机在 xamarin 构建的 iOS 应用程序中自动打印的方法。

Answer 1

这是一个 iOS 错误。我向 Apple Bug Reporter (47180997) 报告，他们给了我一个蹩脚的回应:

Shared printers on Linux will not work with this contactPrinter method. It requires that the printer attributes are returned successfully. We often still send a print job even if the other parts fail.

For these methods to work properly, the server has to be a licensed and correctly implemented AirPrint server. CUPS running somewhere isn’t enough.