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iOS Help please - initWithCoder error when I'm not even using one

W

whitedragon101

macrumors 65816
Original poster
Sep 11, 2008
1,349
339
I just got a message from a user saying the app now crashes when they generate a PDF. I tracked it down and the error is totally weird. No code has changed but after they update to IOS11 this error appears.

Code: 
2017-10-26 02:04:12.170897+0100 Pocket CBT[63876:4962116] -[PDFViewController initWithCoder:]: unrecognized selector sent to instance 0x60400001aab0
2017-10-26 02:04:12.180239+0100 Pocket CBT[63876:4962116] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[PDFViewController initWithCoder:]: unrecognized selector sent to instance 0x60400001aab0'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010dd8e1cb __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010d2a2f41 objc_exception_throw + 48
    2   CoreFoundation                      0x000000010de0e914 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
    3   CoreFoundation                      0x000000010dd11178 ___forwarding___ + 1432
    4   CoreFoundation                      0x000000010dd10b58 _CF_forwarding_prep_0 + 120
    5   UIKit                               0x000000010af8c278 -[UIClassSwapper initWithCoder:] + 246
    6   UIKit                               0x000000010b1de351 UINibDecoderDecodeObjectForValue + 704
    7   UIKit                               0x000000010b1de086 -[UINibDecoder decodeObjectForKey:] + 89
    8   UIKit                               0x000000010af8bf44 -[UIRuntimeConnection initWithCoder:] + 178
    9   UIKit                               0x000000010b1de351 UINibDecoderDecodeObjectForValue + 704
    10  UIKit                               0x000000010b1de4ef UINibDecoderDecodeObjectForValue + 1118
    11  UIKit                               0x000000010b1de086 -[UINibDecoder decodeObjectForKey:] + 89
    12  UIKit                               0x000000010af8b141 -[UINib instantiateWithOwner:options:] + 1262
    13  UIKit                               0x000000010b418026 -[UIStoryboard instantiateViewControllerWithIdentifier:] + 181
    14  UIKit                               0x000000010b42781a -[UIStoryboardSegueTemplate instantiateOrFindDestinationViewControllerWithSender:] + 90
    15  UIKit                               0x000000010b427a5e -[UIStoryboardSegueTemplate _perform:] + 52
    16  UIKit                               0x000000010aca8418 -[UIViewController performSegueWithIdentifier:sender:] + 99
    17  Pocket CBT                          0x0000000109705a51 -[thoughtRecordInfo showDiagram:] + 97
    18  UIKit                               0x000000010ab01ec9 -[UIApplication sendAction:to:from:forEvent:] + 83
    19  UIKit                               0x000000010ac7f1f6 -[UIControl sendAction:to:forEvent:] + 67
    20  UIKit                               0x000000010ac7f513 -[UIControl _sendActionsForEvents:withEvent:] + 450
    21  UIKit                               0x000000010ac7e440 -[UIControl touchesEnded:withEvent:] + 618
    22  UIKit                               0x000000010ab77b1b -[UIWindow _sendTouchesForEvent:] + 2807
    23  UIKit                               0x000000010ab7923e -[UIWindow sendEvent:] + 4124
    24  UIKit                               0x000000010ab1cd96 -[UIApplication sendEvent:] + 352
    25  UIKit                               0x000000010b45efce __dispatchPreprocessedEventFromEventQueue + 2809
    26  UIKit                               0x000000010b461c23 __handleEventQueueInternal + 5957
    27  CoreFoundation                      0x000000010dd312b1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    28  CoreFoundation                      0x000000010ddd0d31 __CFRunLoopDoSource0 + 81
    29  CoreFoundation                      0x000000010dd15c19 __CFRunLoopDoSources0 + 185
    30  CoreFoundation                      0x000000010dd151ff __CFRunLoopRun + 1279
    31  CoreFoundation                      0x000000010dd14a89 CFRunLoopRunSpecific + 409
    32  GraphicsServices                    0x000000010ecd79c6 GSEventRunModal + 62
    33  UIKit                               0x000000010ab0023c UIApplicationMain + 159
    34  Pocket CBT                          0x00000001096ed22f main + 111
    35  libdyld.dylib                       0x000000010f6e3d81 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

This is the result of a modal segue like this :

Code: 
[self performSegueWithIdentifier:@"infoToPDF" sender:self];

the next file is a normal view controller and crashes before it even loads with the error above. The init doesn't even match what I am actually using :

Code: 
#import "PDFViewController.h"
#import "AppDelegate.h"
#import <Foundation/Foundation.h>
#import "GradientBackgroundLayer.h"
#import "SummaryVC.h"

@interface PDFViewController ()

@end

@implementation PDFViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self)
    {
        // Custom initialization
    }
    return self;
}


Any help would be much appreciated.
 
Last edited:
initWithCoder is called on a UIViewController that is loaded through a nib or a storyboard. This was always the case But what is strange is that UIViewController has a initWithCoder implementatin already. If you don't override it the app still shouldn't crash...

Looking at the stack trace though we can see the crash is actually originating from UIClassSwapper. Some interesting info on what that little fella does can be found over here https://gist.github.com/0xced/45daf79b62ad6a20be1c
https://gist.github.com/0xced/45daf79b62ad6a20be1c
This makes me think you might be subclassing something you shouldn't be subclassing?
 
dantastic said:
initWithCoder is called on a UIViewController that is loaded through a nib or a storyboard. This was always the case But what is strange is that UIViewController has a initWithCoder implementatin already. If you don't override it the app still shouldn't crash...

Looking at the stack trace though we can see the crash is actually originating from UIClassSwapper. Some interesting info on what that little fella does can be found over here https://gist.github.com/0xced/45daf79b62ad6a20be1c
This makes me think you might be subclassing something you shouldn't be subclassing?
Click to expand...


The new xCode and IOS11 have just unleashed a ***** storm on me.

The class is just a UIViewController. I finally managed to fix the problem by literally creating new .m and .h files and a new view controller creating identical layout and hooking things up to the new class where I copied and pasted the code in bit by bit. It now works. The fact that no code changed makes me think there are bugs in xCode/ IOS11.

What is really a problem is I noticed that the new xCode has completely changed how it interprets my iPad layout (I have both iPhone and iPad storyboards) so all the components are all over the place. So I can't just recompile and submit an update for the error above as it will break the iPad mode which has no problems on the launched version. I have to figure out why the layout has changed but I suspect I have to recreate and re-hook up the whole layout (arrghhhhhh).
 
The usual cause for that kind of Unrecognized Selector crash is a bad case of Zombies. I'd recommend that you turn on Zombies and see if anything pops up.

initWithNibName isn't doing anything with a view controller from a storyboard. You should probably implement initWithCoder in your PDFViewController if you do any custom initialization (and even if you don't).

It's possible that there was something wrong or old in your storyboard that got updated when you made changes with the new tools.
 
dantastic said:
Oh yea, Xcode is a disaster at the moment.
Click to expand...

PhoneyDeveloper said:
The usual cause for that kind of Unrecognized Selector crash is a bad case of Zombies. I'd recommend that you turn on Zombies and see if anything pops up.

initWithNibName isn't doing anything with a view controller from a storyboard. You should probably implement initWithCoder in your PDFViewController if you do any custom initialization (and even if you don't).

It's possible that there was something wrong or old in your storyboard that got updated when you made changes with the new tools.
Click to expand...

Thanks for the help guys.

After a marathon coding session I fixed the bugs.

I rebuilt my iPad interface from scratch, can't believe I got it done in 24hours. Feet to the flames is a good motivator. I've never had a bug crash a live app.

Not sure what the Zombies are but I will definitely google "Zombies in xCode."

Thanks again
 
In case someobody else will come across this, I had exact the same problem with exact the same class name and I renamed it to PDF2ViewController and then it worked. Perhaps it clashes with Apple's PDFKit.
 
Hmmm, yes. Two classes with the same name could cause the crashlog showed at the top. Because of the way nibs/storyboards are loaded and the lack of namespaces in obj-c it would be possible for the wrong class to be loaded.

Apple's Messages framework was also reported to have unadorned class names like Headers and Message, which could cause conflicts.
 
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