Crash when contentOffset is being updated - ios

Question

let bottomOffset = bottomView.contentOffset.y
let currentOffset = overlayScrollView?.contentOffset.y ?? CGFloat(0)
let totalOffset = (bottomOffset + currentOffset) > 0 ? (bottomOffset + currentOffset) : 0
bottomView.contentOffset.y = 0
overlayScrollView?.contentOffset.y = totalOffset
I am facing several crashes of type EXC_BAD_ACCESS KERN_PROTECTION_FAILURE in app on this line
overlayScrollView?.contentOffset.y = totalOffset
Initially, I thought this is happening because KVO is not being handled properly, that might be message is being sent to deallocated object and observer is not removed.
Moved to new KVO keyPathBased APIs which removed overhead of removing observer. But still this issue is happening. This issue is not reproducible at all on my end.
0 QuartzCore 0x1a42bb938 CA::Layer::writable_state(CA::Transaction*) + 490
1 QuartzCore 0x1a42bba74 CA::Layer::end_change(CA::Transaction*, unsigned int, objc_object*, objc_object*) + 32
2 QuartzCore 0x1a42c4a04 CA::Layer::set_position(CA::Vec2<double> const&, bool) + 312
3 QuartzCore 0x1a42b2dbc -[CALayer setPosition:] + 48
4 QuartzCore 0x1a42b3450 -[CALayer setFrame:] + 424
5 UIKitCore 0x1a3e28df0 -[UIView(Geometry) setFrame:] + 472
6 UIKitCore 0x1a3dcf4b4 -[UIScrollView _layoutHorizontalScrollIndicatorWithBounds:effectiveInset:contentOffset:fraction:additionalInset:cornerAdjust:showing:recalcSize:verticalIndicatorFrame:] + 1320
7 UIKitCore 0x1a3dce89c -[UIScrollView _adjustScrollerIndicators:alwaysShowingThem:] + 1288
8 UIKitCore 0x1a3dbabfc -[UIScrollView setContentOffset:] + 1208
9 UIKitCore 0x1a3b46ed4 -[UITableView setContentOffset:] + 284
10 Foundation 0x1a236dbd8 -[NSObject(NSKeyValueObservingPrivate) _changeValueForKeys:count:maybeOldValuesDict:maybeNewValuesDict:usingBlock:] + 560
11 Foundation 0x1a22b2600 -[NSObject(NSKeyValueObservingPrivate) _changeValueForKey:key:key:usingBlock:] + 68
12 Foundation 0x1a2369614 _NSSetPointValueAndNotify + 300
13 App 0x10488393c partial apply for closure #2 in PageBaseViewController.updatePanView(view:index:) + 540 (PageBaseViewController.swift:540)
14 App 0x1048822d8 partial apply for thunk for #escaping #callee_guaranteed (#guaranteed ZScrollView, #in_guaranteed NSKeyValueObservedChange<CGPoint>) -> () + 4369375960 (<compiler-generated>:4369375960)
15 libswiftFoundation.dylib 0x1a48d6a50 closure #1 in _KeyValueCodingAndObserving.observe<A>(_:options:changeHandler:) + 320
16 libswiftFoundation.dylib 0x1a48d9cc4 specialized NSKeyValueObservation.Helper._swizzle_me_observeValue(forKeyPath:of:change:context:) + 1268
17 libswiftFoundation.dylib 0x1a48d6494 #objc NSKeyValueObservation.Helper._swizzle_me_observeValue(forKeyPath:of:change:context:) + 192
18 Foundation 0x1a236bd70 NSKeyValueNotifyObserver + 288
19 Foundation 0x1a236e188 NSKeyValueDidChange + 324
20 Foundation 0x1a236dc14 -[NSObject(NSKeyValueObservingPrivate) _changeValueForKeys:count:maybeOldValuesDict:maybeNewValuesDict:usingBlock:] + 620
21 Foundation 0x1a22b2600 -[NSObject(NSKeyValueObservingPrivate) _changeValueForKey:key:key:usingBlock:] + 68
22 Foundation 0x1a2369614 _NSSetPointValueAndNotify + 300
23 UIKitCore 0x1a3b386b0 -[UITableView _restoreOrAdjustContentOffsetWithRowCount:initialContentInsetTop:] + 352
24 UIKitCore 0x1a3b27a50 -[UITableView _updateVisibleCellsNow:] + 3552
25 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
26 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
27 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
28 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
29 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
30 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
31 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
32 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
33 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
34 UIKitCore 0x1a3b27a78 -[UITableView _updateVisibleCellsNow:] + 3592
35 UIKitCore 0x1a3b44938 -[UITableView layoutSubviews] + 356
36 UIKitCore 0x1a3e44910 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2544
37 QuartzCore 0x1a42b96dc -[CALayer layoutSublayers] + 288
38 QuartzCore 0x1a42bfe64 CA::Layer::layout_if_needed(CA::Transaction*) + 544
39 QuartzCore 0x1a42cb424 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 140
40 QuartzCore 0x1a4213c20 CA::Context::commit_transaction(CA::Transaction*, double, double*) + 500
41 QuartzCore 0x1a423e970 CA::Transaction::commit() + 668
42 UIKitCore 0x1a39752c0 _afterCACommitHandler + 140
43 CoreFoundation 0x1a102d418 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 32
44 CoreFoundation 0x1a1027a48 __CFRunLoopDoObservers + 588
45 CoreFoundation 0x1a1027fe4 __CFRunLoopRun + 1012
46 CoreFoundation 0x1a10276a8 CFRunLoopRunSpecific + 572
47 GraphicsServices 0x1b76d7570 GSEventRunModal + 160
48 UIKitCore 0x1a3945370 -[UIApplication _run] + 1052
49 UIKitCore 0x1a394a8ec UIApplicationMain + 164
50 App 0x10460b944 main + 15 (main.m:15)
51 libdyld.dylib 0x1a0d06140 start + 4