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: (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: 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 .... )