# Stale view update in \`willSet\` (Observation & SwiftUI)?

**URL:** <https://forums.swift.org/t/stale-view-update-in-willset-observation-swiftui/90131>\
**Category:** Using Swift\
**Tags:** swiftui, observation\
**Created:** [October 18, 2026, 6:36am UTC](https://forums.swift.org/t/stale-view-update-in-willset-observation-swiftui/90131 "2026-10-18T06:36:12Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![oscbyspro](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/oscbyspro/32/23689_2.png) [@oscbyspro](https://forums.swift.org/u/oscbyspro)\
**Post date:** [October 18, 2026, 6:36am UTC](https://forums.swift.org/t/stale-view-update-in-willset-observation-swiftui/90131/1 "2026-10-18T06:36:12Z")

</div>

I have encountered a synchronization issue while developing my iOS app where two parts of a SwiftUI view graph disagree on the same `@MainActor` `@Observable` view model state. Imagine two views that access `currentValue` in their bodies. One shows `currentValue`, and the other shows `newValue` after running this line of view model code:

```swift
self.currentValue = newValue

```

After manually expanding the `@ObservationTracked` macro and adding `let _ = Self._printChanges()` to the relevant view bodies, it became clear that the stale part of the view graph runs its body and consumes the change notification in `willSet` and doesn't perform any subsequent updates after `self._currentValue = newValue` or `didSet`.

```swift
self._$observationRegistrar.willSet(self, keyPath: \.currentValue) // stale view is updated in will set
self._currentValue = newValue
self._$observationRegistrar .didSet(self, keyPath: \.currentValue) // stale view does not honor did set

```

This notion is reinforced by the fact that the obvious diagnostic fix works. If the issue is that change notification is consumed before the new value is available, then we can request a view update cycle later to resolve it:

```swift
self.currentValue = newValue
#warning("please send help")
self.withMutation(keyPath: \.currentValue, {})

```

Obviously, this is not a permanent fix. I’m just wondering whether this is a known Observation or SwiftUI bug. I found this issue on GitHub ([`withObservationTracking` can miss concurrent/coincident updates · Issue #83359 · swiftlang/swift · GitHub](https://github.com/swiftlang/swift/issues/83359)), but I’m not sure whether it’s related. If I had a minimal reproduction example, I would have shared it.