从 Url 创建一个工作 UIPrinter 对象以进行无对话打印 [英] Creating a working UIPrinter object from Url for dialogue-free printing

问题描述

场景:引导模式锁定的应用程序接受一些用户输入(姓名等)并打印出票证.用户无法选择打印机.

我计划的解决方案是保存打印机的 URL，我拥有并采用以下形式:

My planned solution was to save the URL of the printer, which I have and is in the form of:

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

从这个存储的字符串构建 UIPrinter 对象:

To build the UIPrinter object from this stored string:

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

然后我打电话:

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.

However, when using a UIPrinter object returned from UIPrinterPickerController (as shown below) it all works.

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;
        });

我什至尝试从 PrinterPicker 获取 UIPrinter 对象，并尝试使用从 PrinterPicker 获取的 UIPrinter 对象中的 url 使用 UIPrinter.FromUrl 构建一个新的 UIPrinter.

I have even tried getting the UIPrinter object from PrinterPicker, and trying to build a new UIPrinter with UIPrinter.FromUrl using the url from the UIPrinter object taken from PrinterPicker.

我只能创建一个可以工作的 UIPrinter 对象，而没有直接使用 UIPrinterPickerController 中的对象，如下所示:

I was only able to create a working UIPrinter object without directly using the one from UIPrinterPickerController like so:

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"打印机的方法，并使用该打印机在 xamarin 构建的 iOS 应用程序中自动打印.

Summary What I need is a way to 'remember' a printer, and use that printer to print automatically in a xamarin-built iOS app.

推荐答案

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复:

This is an iOS bug. I reported to Apple Bug Reporter (47180997) and they gave me a lame response:

Linux 上的共享打印机不适用于此 contactPrinter 方法.它要求成功返回打印机属性.即使其他部分出现故障，我们仍然经常发送打印作业.

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.

要使这些方法正常工作，服务器必须是获得许可且正确实施的 AirPrint 服务器.在某处运行 CUPS 是不够的.

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

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