Crash triggered by custom font action

Question

Created Jun ’20

Replies 5

Boosts 0

Views 2.2k

Participants 6

In iOS14 Beta, A crash will triggered when we use keyboard to input text. After checking our code , we found that it's related with custom font action.

In our APP, we allow users to select different font according to their reading habit.

We want to know:

Will this crash be fixed in release version？
Is there any other suggested ways to set custom fonts？

custom font code:

Code Block Objc+ (void)load
 {
 		Method original = class_getClassMethod(self, NSSelectorFromString(@"systemFontOfSize:"));
  	 Method swizzled = class_getClassMethod(self, @selector(xxxx_systemFontOfSize:));
  	 method_exchangeImplementations(original, swizzled);
}
+ (UIFont *)xxxx_systemFontOfSize:(CGFloat)fontSize 
{
  return [UIFont fontWithName:@"FZYaSongS-R-GB"	size:fontSize];
}

The crash stack is as follow:

Code Block 2020-06-24 11:57:03.781098+0800 XXXXX[83196:2361602] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCache setObject:forKey:cost:]: attempt to insert nil value (key: 0)'
* First throw call stack:
(
	0	 CoreFoundation											0x00007fff20434f16 exceptionPreprocess + 242
	1	 libobjc.A.dylib										 0x00007fff2017454e objc_exception_throw + 48
	2	 CoreFoundation											0x00007fff20460566 -[NSCache removeObjectForKey:] + 0
	3	 UIKitCore													 0x00007fff23eb2694 +[UISegmentedControl _fontForTraitCollection:size:selected:] + 339
	4	 UIKitCore													 0x00007fff23ea0559 -[UISegment _attributedTextForState:selected:forceSelectedAppearance:] + 502
	5	 UIKitCore													 0x00007fff23ea0229 -[UISegment _updateTextColors] + 107
	6	 UIKitCore													 0x00007fff23ea3132 -[UISegment setObjectValue:] + 2061
	7	 UIKitCore													 0x00007fff23e9c0cf -[UISegment initWithInfo:size:barStyle:tintColor:appearanceStorage:position:autosizeText:adjustsForContentSizeCategory:] + 412
	8	 UIKitCore													 0x00007fff23eb29c7 -[UISegmentedControl _createSegmentAtIndex:position:withInfo:] + 178
	9	 UIKitCore													 0x00007fff23eb2a3a -[UISegmentedControl _createAndAddSegmentAtIndex:position:withInfo:] + 36
	10	UIKitCore													 0x00007fff23eb2e0a 55-[UISegmentedControl _insertSegment:withInfo:animated:]_block_invoke + 66
	11	UIKitCore													 0x00007fff24a677d1 +[UIView(Animation) performWithoutAnimation:] + 84
	12	UIKitCore													 0x00007fff23eb2c31 -[UISegmentedControl _insertSegment:withInfo:animated:] + 376
	13	TextInputUI												 0x00007fff35673eb2 -[TUICandidateSortControl setTitles:] + 433
	14	TextInputUI												 0x00007fff3564d57f -[TUICandidateView updateSortControlTitlesIfNeeded] + 215
	15	TextInputUI												 0x00007fff3564d417 -[TUICandidateView setCandidateResultSet:] + 100
	16	UIKitCore													 0x00007fff2416bfae -[UIKeyboardCandidateController setCandidateResultSet:] + 515
	17	UIKitCore													 0x00007fff2416c3ff -[UIKeyboardCandidateController setCandidates:type:inlineText:inlineRect:maxX:layout:] + 117
	18	UIKitCore													 0x00007fff2432824d -[UIKeyboardImpl updateTextCandidateView] + 3335
	19	UIKitCore													 0x00007fff2432514c -[UIKeyboardImpl setCandidates:] + 396
	20	UIKitCore													 0x00007fff24323e28 -[UIKeyboardImpl updateCandidateDisplayAsyncWithCandidateSet:] + 1193
	21	UIKitCore													 0x00007fff2431533d -[UIKeyboardImpl inputManagerDidGenerateCandidatesForRequest:resultSet:] + 697
	22	UIKitCore													 0x00007fff24314d5b __78-[UIKeyboardImpl generateCandidatesAsynchronouslyWithRange:selectedCandidate:]_block_invoke_3 + 94
	....
)

Boost

Answer 1

Frameworks Engineer OP

Apple

Jun ’20

Since you're swizzling, I'd say "no". :)
UIAppearance provides this functionality: https://developer.apple.com/documentation/uikit/uiappearance. You will have to configure appearance for all relevant controls, though.

5

Answer 2

jblahunka OP

Jul ’20

Hi,

Swizzling is one of the most straightforward ways to replace fonts in the whole application seamlessly. Is there a chance Apple will provide an API for replacing system fonts?

0

Answer 3

oceantang OP

Jul ’20

same problem..

0

Answer 4

jm_kayak OP

Jul ’20

On Xcode 12.0 beta 2 (12A6163b) it seems that initializing a segmented control with an arbitrary string once before swizzling the UIFont selectors fixes the crash.

Code Block  private var isAppFontSetUp = false
func setUpAppFont() {
		guard !isAppFontSetUp else {
				return
		}
+
+		let _ = UISegmentedControl(items: ["foo"])
		swizzle()
}

However, I am unsure if this fixes the crash for good since the root cause seems to lie in a cache (which might get purged again at some point).

2

Answer 5

nikita16 OP

Aug ’20

It is fixed in iOS 14 beta 3, right?
I see crashes only in beta 1 and 2

0