fix(ios): stabilize blur intensity after mount with CADisplayLink

[kOOnzTe]

Summary

Stabilize BlurEffectView during the first frames after mount, window attach, and foreground return.

Problem

BlurEffectView relies on a paused UIViewPropertyAnimator to preserve custom blur intensity. In practice, UIKit can still invalidate that animator during the first few frames after:

• initial mount
• moving into a window
• returning from background

When that happens, the blur may briefly render with the wrong material state or appear unblurred until a later rebuild.

Solution

This change adds a short, bounded CADisplayLink stabilization pass:

• start a 3-frame rebuild window after blur updates and didMoveToWindow
• stop immediately when the view leaves the window
• clean up the display link in deinit

This keeps the existing animator-based intensity approach, but makes it more resilient during UIKit transition timing.

Why this is safe

• the stabilization window is intentionally tiny at 3 visible frames
• work only runs while the view is attached to a window
• existing blur behavior is preserved after the stabilization pass finishes
• cleanup is explicit both on window detach and deallocation

Testing

• mounted a screen containing BlurEffectView and verified blur stays applied on first render
• navigated in and out of the screen and verified no temporary unblurred flash
• backgrounded and foregrounded the app and verified blur intensity is restored cleanly

[coderabbitai]

📝 Walkthrough

Walkthrough

BlurEffectView adds a bounded CADisplayLink stabilization period that rebuilds the blur animator after blur updates and window transitions, stops when detached, and is invalidated during teardown.

Changes

Blur stabilization

Layer / File(s)	Summary
Stabilization triggers ios/Views/BlurEffectView.swift	Blur updates and window attachment rebuild the animator and start stabilization; window detachment stops it.
Display-link stabilization and cleanup ios/Views/BlurEffectView.swift	Display-link ticks rebuild the animator for a bounded frame budget, with explicit invalidation during teardown.

Estimated code review effort: 3 (Moderate) | ~15–30 minutes

Possibly related PRs

• sbaiahmed1/react-native-blur#102: Modifies blur animator setup and lifecycle in the same view methods.
• sbaiahmed1/react-native-blur#110: Changes blur animator rebuild behavior in the same file.
• sbaiahmed1/react-native-blur#114: Adds another animator rebuild path in BlurEffectView.

Suggested reviewers: DanielAraldi

Sequence Diagram(s)

sequenceDiagram
  participant UIWindow
  participant BlurEffectView
  participant CADisplayLink
  UIWindow->>BlurEffectView: attach view
  BlurEffectView->>BlurEffectView: rebuildAnimator()
  BlurEffectView->>CADisplayLink: schedule stabilization
  CADisplayLink->>BlurEffectView: handleStabilizationTick()
  BlurEffectView->>BlurEffectView: rebuildAnimator()
  BlurEffectView->>CADisplayLink: invalidate after frame budget

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main iOS blur stabilization change and mentions the key implementation detail.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

ios/Views/BlurEffectView.swift (1)

86-101: 🩺 Stability & Availability | 🔵 Trivial | ⚡ Quick win

Break the CADisplayLink retain cycle
CADisplayLink(target: self, ...) keeps BlurEffectView alive through stabilizationDisplayLink, so deallocation can be delayed until the 3-frame window ends. A weak proxy would let deinit run immediately if the view is removed or the app backgrounds mid-stabilization.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@ios/Views/BlurEffectView.swift` around lines 86 - 101, Break the
CADisplayLink retain cycle in startStabilizationIfNeeded by targeting a weak
proxy object instead of BlurEffectView directly; have the proxy forward
handleStabilizationTick to the view without retaining it, while preserving
existing stabilizationDisplayLink invalidation and callback behavior.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@ios/Views/BlurEffectView.swift`:
- Around line 86-101: Break the CADisplayLink retain cycle in
startStabilizationIfNeeded by targeting a weak proxy object instead of
BlurEffectView directly; have the proxy forward handleStabilizationTick to the
view without retaining it, while preserving existing stabilizationDisplayLink
invalidation and callback behavior.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 5fd8cecb-8c4f-494e-9c72-2fd1a1087b0c

📥 Commits

Reviewing files that changed from the base of the PR and between 6df7e7f and 11b7b65.

📒 Files selected for processing (1)

• ios/Views/BlurEffectView.swift

[omer-ayhan]

nice work🚀

[gorkemozkan]

Well done! @kOOnzTe

[sbaiahmed1]

Released in 4.7.1