My App crash on iPad before even application:didFinishLaunchingWithOptions: - ios

Question

My app is crashing with the following crashlog when ran on ipad.
It just work fine on iphone devices.
As you might notice, it crash while trying to setup the window. I have searched everywhere but don't see such an issue in any other topic.
Thanks for you help.
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** setObjectForKey: object cannot be nil (key: NSParagraphStyle)'
*** First throw call stack:
(
0 CoreFoundation 0x000000010e38ff35 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x000000010e028bb7 objc_exception_throw + 45
2 CoreFoundation 0x000000010e296998 -[__NSDictionaryM setObject:forKey:] + 968
3 UIKit 0x000000010ca99d2d -[UILabel _setLineBreakMode:] + 529
4 UIKit 0x000000010cb7a572 -[UIButtonLabel setLineBreakMode:] + 93
5 UIKit 0x000000010cb86e5c -[UIButton _setupTitleViewRequestingLayout:] + 308
6 UIKit 0x000000010cb7ed15 -[UIButton titleLabel] + 51
7 UIKit 0x000000010cd3c6d8 -[UIZoomViewController loadView] + 476
8 UIKit 0x000000010c9f67f9 -[UIViewController loadViewIfRequired] + 75
9 UIKit 0x000000010c9f6c8e -[UIViewController view] + 27
10 UIKit 0x000000010cd3bfa4 -[UIZoomViewController init] + 78
11 UIKit 0x000000010cd39eeb -[UIClassicController _setupWindow] + 544
12 UIKit 0x000000010cd39b7c +[UIClassicController sharedClassicController] + 140
13 UIKit 0x000000010c8e47dd -[UIApplication _handleApplicationActivationWithScene:transitionContext:completion:] + 666
14 UIKit 0x000000010c8e42ae __88-[UIApplication _handleApplicationLifecycleEventWithScene:transitionContext:completion:]_block_invoke + 138
15 UIKit 0x000000010c8e4215 -[UIApplication _handleApplicationLifecycleEventWithScene:transitionContext:completion:] + 349
16 UIKit 0x000000010c8cf31a -[UIApplication scene:didUpdateWithDiff:transitionContext:completion:] + 486
17 UIKit 0x000000010c8cedb8 -[UIApplication workspace:didCreateScene:withTransitionContext:completion:] + 336
18 FrontBoardServices 0x000000011064f612 __56-[FBSWorkspace client:handleCreateScene:withCompletion:]_block_invoke_2 + 265
19 FrontBoardServices 0x000000011065e2a3 __31-[FBSSerialQueue performAsync:]_block_invoke + 16
20 CoreFoundation 0x000000010e2c553c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
21 CoreFoundation 0x000000010e2bb285 __CFRunLoopDoBlocks + 341
22 CoreFoundation 0x000000010e2bb045 __CFRunLoopRun + 2389
23 CoreFoundation 0x000000010e2ba486 CFRunLoopRunSpecific + 470
24 UIKit 0x000000010c8ce669 -[UIApplication _run] + 413
25 UIKit 0x000000010c8d1420 UIApplicationMain + 1282
26 Edyn 0x0000000109704323 main + 115
27 libdyld.dylib 0x000000010ebd2145 start + 1
28 ??? 0x0000000000000001 0x0 + 1
)
Edit 1
The problem is more complicated than I thought. Here is what I have done.
Implemented method swizzling around [UIButtonLabel setLineBreakMode:] so that I can see what is causing to use nil for the LineBreakMode. I found out that if lineBreakMode is set to something else than NSLineBreakByWordWrapping it ultimately crash.
To temporary make it work I am forcing the lineBreakMode to NSLineBreakByWordWrapping which is not a big deal in this case because the label is never seens in my app.
Edit 2
After fixing the issue with lineBreakMode, I am now getting the same issue but this time with [UILabel setShadow:].
Note that it crash on label where I didn't change anything to the shadow attributes (color, offset or blurRadius).
I also get the same issue but this time with paragraphStyle
Which mean I can't definitely not keep using this approach as it seems to be something broken in what's happening.
Edit 3
When I change the deployment target of my app to universal, I don't have any of the above issues.

Answer 1

I was overriding those two functions in a category and guess what? those function seems to be called by ios even before you get control of the app in your AppDelegate. And for some reason on ipad this return nil.
Removing the category fixed the problem.
+ (id)systemFontOfSize:(CGFloat)sz {
return [UIFont fontWithName:#"HelveticaNeue-Regular" size:sz];
}
+ (id)boldSystemFontOfSize:(CGFloat)sz {
return [UIFont fontWithName:#"HelveticaNeue-Bold" size:sz];
}