Fix sign in alert shown inconsistently when triggered in viewDidAppear (#10288)

* Simple fix for #8096

* Update FirebaseAppDistribution/CHANGELOG.md

Co-authored-by: Nick Cooke <[email protected]>

Co-authored-by: Nick Cooke <[email protected]>

Author: tejasd

FirebaseAppDistribution/CHANGELOG.md

@@ -1,3 +1,6 @@
+# 10.1.0
+- [fixed] Fixed inconsistent sign in prompts in single scene apps (#8096).
+
 # 9.0.0
 - [fixed] Marked `releaseNotes` as `nullable` as they don't always exist (#8602).
 - [fixed] **Breaking change:** Fixed an ObjC-to-Swift API conversion error where`checkForUpdate()`

FirebaseAppDistribution/Sources/FIRAppDistributionUIService.m

@@ -213,7 +213,15 @@ - (void)initializeUIState {
 
     if (foregroundedScene) {
       self.window = [[UIWindow alloc] initWithWindowScene:foregroundedScene];
+    } else if ([UIApplication sharedApplication].connectedScenes.count == 1) {
+      // There are situations where a scene isn't considered foreground in viewDidAppear
+      // and this fixes the issue in single scene apps.
+      // https://github.com/firebase/firebase-ios-sdk/issues/8096
+      UIWindowScene *scene =
+          (UIWindowScene *)[UIApplication sharedApplication].connectedScenes.anyObject;
+      self.window = [[UIWindow alloc] initWithWindowScene:scene];
     } else {
+      // TODO: Consider using UISceneDidActivateNotification.
       FIRFADInfoLog(@"No foreground scene found.");
       self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
     }