Change voiceNotificationText to be NSAttributedString to allow it…

… set priority for announcement.

PiperOrigin-RevId: 559904885

components/Snackbar/src/MDCSnackbarMessage.h

@@ -176,6 +176,11 @@ extern NSString *__nonnull const MDCSnackbarMessageBoldAttributeName;
  */
 @property(nonatomic, copy, nullable) NSString *accessibilityLabel;
 
+/**
+ An attributed label that can be used to set priority for the accessibility announcement.
+ */
+@property(nonatomic, copy, nullable) NSAttributedString *attributedAccessibilityLabel;
+
 /**
  Redeclaration from UIAccessibility to make clear that this class supports accessibility hints.
  */
@@ -184,7 +189,7 @@ extern NSString *__nonnull const MDCSnackbarMessageBoldAttributeName;
 /**
  Text that should be read when the message appears on screen and VoiceOver is enabled.
  */
-@property(nonatomic, readonly, nullable) NSString *voiceNotificationText;
+@property(nonatomic, readonly, nullable) NSAttributedString *voiceNotificationText;
 
 /**
  By setting this property to @c YES, the Ripple component will be used instead of Ink

components/Snackbar/src/MDCSnackbarMessage.m

@@ -126,11 +126,24 @@ - (void)setDuration:(NSTimeInterval)duration {
 
 #pragma mark - A11y
 
-- (NSString *)voiceNotificationText {
-  if ([self.accessibilityLabel length]) {
-    return self.accessibilityLabel;
+- (void)setAccessibilityLabel:(NSString *)accessibilityLabel {
+  if (accessibilityLabel == nil) {
+    self.attributedAccessibilityLabel = nil;
   } else {
-    return self.text;
+    self.attributedAccessibilityLabel =
+        [[NSAttributedString alloc] initWithString:[accessibilityLabel copy]];
+  }
+}
+
+- (NSString *)accessibilityLabel {
+  return [self.attributedAccessibilityLabel string];
+}
+
+- (NSAttributedString *)voiceNotificationText {
+  if (self.attributedAccessibilityLabel) {
+    return self.attributedAccessibilityLabel;
+  } else {
+    return self.attributedText;
   }
 }