将UIPrinter保存到NSUserDefaults

本文介绍了将UIPrinter保存到NSUserDefaults的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在尝试保存这样的UIPrinter对象.

I am trying to save a UIPrinter object like this.

-(IBAction)setPrinterInSettings:(id)sender{ UIPrinterPickerController *picker = [UIPrinterPickerController printerPickerControllerWithInitiallySelectedPrinter:self.SavedPrinter]; [picker presentFromRect:self.settingsButton.frame inView:self.view animated:YES completionHandler:^(UIPrinterPickerController *controller, BOOL userDidSelect, NSError *err) { if (userDidSelect) { self.SavedPrinter = controller.selectedPrinter; NSLog(@"self.SavedPrinter == %@",self.SavedPrinter); [self saveCustomObject:self.SavedPrinter key:@"SavedPrinter"]; [[NSUserDefaults standardUserDefaults] setObject:self.SavedPrinter forKey:@"SavedPrinter"]; [[NSUserDefaults standardUserDefaults] synchronize]; } }]; }

当我尝试保存在[[NSUserDefaults standardUserDefaults] setObject:self.SavedPrinter forKey:@"SavedPrinter"];时，它崩溃了，并且显示此消息为错误-[UIPrinter encodeWithCoder:]: unrecognized selector sent to instance 0x7fb204062760.我需要它来记住用户选择的打印机，并且即使应用程序退出后台也要记住它.如果有人可以帮助，那就太好了！

It crashes when I try to save at [[NSUserDefaults standardUserDefaults] setObject:self.SavedPrinter forKey:@"SavedPrinter"]; and I get this message as a error -[UIPrinter encodeWithCoder:]: unrecognized selector sent to instance 0x7fb204062760. I need it to remember what printer the user picked and remember it even when the app goes out of the background. If any one could help that would be great!

推荐答案

您不能在NSUserDefaults中存储UIPrinter实例.您可以做的就是保存打印机的URL，然后在您的应用再次启动并且需要UIPrinter时，从NSUserDefaults读取URL并使用UIPrinter printerWithURL:.

You can't store a UIPrinter instance in NSUserDefaults. What you can do is save the printer's URL and then when your app starts again and you need the UIPrinter, read the URL from NSUserDefaults and use UIPrinter printerWithURL:.