UIPrintInteractionController's printToPrinter crash in 'lookupLastUsedPrinter' API call.

Question

sindhusha OP

Created Jul ’22

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Participants 2

Hi,

We are seeing following crash in our codebase (iOS 15) with following call stack in UIPrintInteractionController.
Could anyone please help with your inputs on how we can address following "UIPrintInteractionController's printToPrinter api crash"

Crash stack

uncaught ObjC exception, reason: -[PKPrinter _internalPrinter]: unrecognized selector sent to instance 

Last Exception Backtrace:
2   libobjc.A.dylib                      objc_exception_throw (??:0)w + 
3   CoreFoundation                       __CFOAInitializeNSObject (??:0)3 + 
4   CoreFoundation                       ___forwarding___ (??:0)3 + 
5   CoreFoundation                       __CFRunLoopDoTimers (??:0)0 + 
6   UIKitCore                            __51-[UIPrintPanelViewController lookupLastUsedPrinter]_block_invoke (??:0)5 + 
7   UIKitCore                            -[UIPrintPanelViewController loadView] (??:0)5 + 
8   UIKitCore                            __88-[UIPrintInteractionController _generatePDFInRange:useFullRange:withQuality:completion:]_block_invoke (??:0)5 + 
9   UIKitCore                            -[UIPrintInteractionController printToPrinter:completionHandler:] (??:0)5 + 
10  UIKitCore                            -[UIPrintInteractionController _completePrintPageWithError:] (??:0)5 + 
11  UIKitCore                            -[UIPrintInteractionController printToPrinter:completionHandler:] (??:0)5 +

Codebase that resulted above crash

UIPrintInteractionController *printController = [UIPrintInteractionController sharedPrintController];
UIPrintInteractionCompletionHandler completionHandler = ^(UIPrintInteractionController *printControllerT, BOOL completed, NSError *error) {
  [printControllerT setDelegate:nil];                          
};
[printController setDelegate:printDelegate];
[printController setPrintingItem:rurlPrintJob];                    
[printController presentAnimated:YES completionHandler:completionHandler];

More info

meanwhile I have found one apple thread where its mentioned that “App Crash when using print of UIPrintInteractionController” ==>https://developer.apple.com/forums/thread/689876.
Above thread suggested to use printer.contactPrinter instead of printerController.print.Since our current codebase used default iOS codepath(printToPrinter) with ‘[[UIPrintInteractionController sharedPrintController]presentAnimated:YES completionHandler:completionHandler]]’ api call , I am not able to apply this suggestion in current codebase.

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Answer 1

lxbndr OP

Apr ’23

I believe I saw your question on SO, but decided to reply here as well just to share our solution more widely.

We had exact same issue for a while and finally were able to reproduce it and look for a workaround.

Reproducing

The crash is 100% triggered with these steps:

Set up and present UIPrintInteractionController with UIPrintInfo:

let pic = UIPrintInteractionController.shared
pic.printInfo = UIPrintInfo.printInfo()
pic.printingItem = ...
pic.present(animated: true)

Actually print something
In some other code place set up and present UIPrintInteractionController without UIPrintInfo:

let pic = UIPrintInteractionController.shared
pic.printingItem = ...
pic.present(animated: true) &#x2F;&#x2F; Will crash

Solution

Always specify UIPrintInfo for UIPrintIneractionController:

pic.printInfo = UIPrintInfo.printInfo() &#x2F;&#x2F; Prevents crash

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