feat: Exposes iOS prefersCrossFadeTransitions

Author: gabrieldonadel

Libraries/Components/AccessibilityInfo/AccessibilityInfo.js

@@ -179,6 +179,31 @@ const AccessibilityInfo = {
     });
   },
 
+  /**
+   * Query whether reduce motion and prefer cross-fade transitions settings are currently enabled.
+   *
+   * Returns a promise which resolves to a boolean.
+   * The result is `true` when  prefer cross-fade transitions is enabled and `false` otherwise.
+   *
+   * See https://reactnative.dev/docs/accessibilityinfo#prefersCrossFadeTransitions
+   */
+  prefersCrossFadeTransitions(): Promise<boolean> {
+    return new Promise((resolve, reject) => {
+      if (Platform.OS === 'android') {
+        return Promise.resolve(false);
+      } else {
+        if (NativeAccessibilityManagerIOS != null) {
+          NativeAccessibilityManagerIOS.getCurrentPrefersCrossFadeTransitionsState(
+            resolve,
+            reject,
+          );
+        } else {
+          reject(null);
+        }
+      }
+    });
+  },
+
   /**
    * Query whether reduced transparency is currently enabled.
    *

Libraries/Components/AccessibilityInfo/NativeAccessibilityManager.js

@@ -28,6 +28,10 @@ export interface Spec extends TurboModule {
     onSuccess: (isReduceMotionEnabled: boolean) => void,
     onError: (error: Object) => void,
   ) => void;
+  +getCurrentPrefersCrossFadeTransitionsState: (
+    onSuccess: (prefersCrossFadeTransitions: boolean) => void,
+    onError: (error: Object) => void,
+  ) => void;
   +getCurrentReduceTransparencyState: (
     onSuccess: (isReduceTransparencyEnabled: boolean) => void,
     onError: (error: Object) => void,

React/CoreModules/RCTAccessibilityManager.h

@@ -23,6 +23,7 @@ extern NSString *const RCTAccessibilityManagerDidUpdateMultiplierNotification; /
 @property (nonatomic, assign) BOOL isGrayscaleEnabled;
 @property (nonatomic, assign) BOOL isInvertColorsEnabled;
 @property (nonatomic, assign) BOOL isReduceMotionEnabled;
+@property (nonatomic, assign) BOOL prefersCrossFadeTransitions;
 @property (nonatomic, assign) BOOL isReduceTransparencyEnabled;
 @property (nonatomic, assign) BOOL isVoiceOverEnabled;
 

React/CoreModules/RCTAccessibilityManager.mm

@@ -76,6 +76,13 @@ - (instancetype)init
                                                  name:UIAccessibilityReduceMotionStatusDidChangeNotification
                                                object:nil];
 
+      if (@available(iOS 14.0, *)) {
+          [[NSNotificationCenter defaultCenter] addObserver:self
+                                                   selector:@selector(prefersCrossFadeTransitionsStatusDidChange:)
+                                                       name:UIAccessibilityPrefersCrossFadeTransitionsStatusDidChangeNotification
+                                                     object:nil];
+      }
+
     [[NSNotificationCenter defaultCenter] addObserver:self
                                              selector:@selector(reduceTransparencyStatusDidChange:)
                                                  name:UIAccessibilityReduceTransparencyStatusDidChangeNotification
@@ -91,6 +98,7 @@ - (instancetype)init
     _isGrayscaleEnabled = UIAccessibilityIsGrayscaleEnabled();
     _isInvertColorsEnabled = UIAccessibilityIsInvertColorsEnabled();
     _isReduceMotionEnabled = UIAccessibilityIsReduceMotionEnabled();
+    _prefersCrossFadeTransitions = UIAccessibilityPrefersCrossFadeTransitions();
     _isReduceTransparencyEnabled = UIAccessibilityIsReduceTransparencyEnabled();
     _isVoiceOverEnabled = UIAccessibilityIsVoiceOverRunning();
   }
@@ -169,6 +177,19 @@ - (void)reduceMotionStatusDidChange:(__unused NSNotification *)notification
   }
 }
 
+- (void)prefersCrossFadeTransitionsStatusDidChange:(__unused NSNotification *)notification
+{
+  BOOL newPrefersCrossFadeTransitionsEnabled = UIAccessibilityPrefersCrossFadeTransitions();
+  if (_prefersCrossFadeTransitions != newPrefersCrossFadeTransitionsEnabled) {
+    _prefersCrossFadeTransitions = newPrefersCrossFadeTransitionsEnabled;
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+    [[_moduleRegistry moduleForName:"EventDispatcher"] sendDeviceEventWithName:@"prefersCrossFadeTransitionsChanged"
+                                                                          body:@(_prefersCrossFadeTransitions)];
+#pragma clang diagnostic pop
+  }
+}
+
 - (void)reduceTransparencyStatusDidChange:(__unused NSNotification *)notification
 {
   BOOL newReduceTransparencyEnabled = UIAccessibilityIsReduceTransparencyEnabled();
@@ -358,6 +379,13 @@ static void setMultipliers(
   onSuccess(@[ @(_isReduceMotionEnabled) ]);
 }
 
+RCT_EXPORT_METHOD(getCurrentPrefersCrossFadeTransitionsState
+                  : (RCTResponseSenderBlock)onSuccess onError
+                  : (__unused RCTResponseSenderBlock)onError)
+{
+  onSuccess(@[ @(_prefersCrossFadeTransitions) ]);
+}
+
 RCT_EXPORT_METHOD(getCurrentReduceTransparencyState
                   : (RCTResponseSenderBlock)onSuccess onError
                   : (__unused RCTResponseSenderBlock)onError)

packages/rn-tester/js/examples/Accessibility/AccessibilityExample.js

@@ -1127,6 +1127,11 @@ class DisplayOptionsStatusExample extends React.Component<{}> {
           optionChecker={AccessibilityInfo.isReduceMotionEnabled}
           notification={'reduceMotionChanged'}
         />
+        <DisplayOptionStatusExample
+          optionName={'Prefer Cross'}
+          optionChecker={AccessibilityInfo.prefersCrossFadeTransitions}
+          notification={'prefersCrossFadeTransitionsChanged'}
+        />
         <DisplayOptionStatusExample
           optionName={'Screen Reader'}
           optionChecker={AccessibilityInfo.isScreenReaderEnabled}