fix(ios): blur flicker when dismissing sheet with backgroundBlur (#633)

* fix(ios): blur flicker when dismissing sheet with backgroundBlur

Hide UIVisualEffectView at the end of dismiss transition to prevent
flicker/flash at the bottom edge of the sheet.

Fixes #614

* docs: add changelog entry for #633

Author: lodev09

CHANGELOG.md

@@ -10,6 +10,7 @@
 
 ### 🐛 Bug fixes
 
+- **iOS**: Fixed blur flicker/flash at the bottom when dismissing sheet with `backgroundBlur` enabled. ([#633](https://github.com/lodev09/react-native-true-sheet/pull/633) by [@lodev09](https://github.com/lodev09))
 - **Android**: Fixed `NoSuchMethodError` crash on Android < 11 (API 30) when presenting a sheet with grabber accessibility. ([#606](https://github.com/lodev09/react-native-true-sheet/pull/606) by [@Mohamed-kassim](https://github.com/Mohamed-kassim))
 - **iOS**: Fixed keyboard scroll positioning when sheet auto-expands from a smaller detent. ([#592](https://github.com/lodev09/react-native-true-sheet/pull/592) by [@lodev09](https://github.com/lodev09))
 - **Android**: Fixed dead state after rapid present/dismiss cycles. ([#593](https://github.com/lodev09/react-native-true-sheet/pull/593) by [@lodev09](https://github.com/lodev09))

ios/TrueSheetViewController.mm

@@ -200,6 +200,8 @@ - (void)viewDidLoad {
 - (void)viewWillAppear:(BOOL)animated {
   [super viewWillAppear:animated];
 
+  _blurView.alpha = 1;
+
   if (!_isPresented) {
     UIViewController *presenter = self.presentingViewController;
     if ([presenter isKindOfClass:[TrueSheetViewController class]]) {
@@ -475,6 +477,12 @@ - (void)handleTransitionTracker {
     if (self.currentPosition >= self.screenHeight) {
       CGFloat position = fmax(_lastEmittedPositionState.position, layerPosition);
 
+      // Hide blur at the end of dismiss to prevent UIVisualEffectView
+      // from causing a flicker/flash at the bottom edge of the sheet.
+      if (self.screenHeight - position < 1) {
+        _blurView.alpha = 0;
+      }
+
       [self emitWillDismissEvents];
       [self emitChangePositionDelegateWithPosition:position realtime:YES debug:@"transition out"];