fix: Optimize alert operations

WebDriverAgentLib/Categories/XCUIApplication+FBAlert.h

@@ -8,6 +8,8 @@
 
 #import <XCTest/XCTest.h>
 
+#import "FBXCElementSnapshot.h"
+
 NS_ASSUME_NONNULL_BEGIN
 
 @interface XCUIApplication (FBAlert)
@@ -16,19 +18,24 @@ NS_ASSUME_NONNULL_BEGIN
 extern NSString *const FB_SAFARI_APP_NAME;
 
 /**
- Retrieve the current alert element
+ Retrieve the snapshot of the currently displayed alert, if any, using a
+ single upfront application snapshot and purely in-memory tree traversal for
+ all subsequent type/candidate checks - no further accessibility round trips
+ are made beyond the one it takes to obtain the application snapshot itself.
 
- @return Alert element instance
+ @return Alert snapshot instance, or nil if no alert is present
  */
-- (nullable XCUIElement *)fb_alertElement;
+- (nullable id<FBXCElementSnapshot>)fb_alertSnapshot;
 
 /**
- Retrieve an alert element hosted by the iOS 18+ limited access permission prompt
- process. See https://github.com/appium/appium/issues/20591
+ Retrieve the application hosting the iOS 18+ limited access permission prompt,
+ cheaply gated on its running state so callers can avoid resolving its alert
+ snapshot when the prompt process isn't in the foreground.
+ See https://github.com/appium/appium/issues/20591
 
- @return Alert element instance if the prompt is present, otherwise nil
+ @return The prompt application if it is running in the foreground, otherwise nil
  */
-+ (nullable XCUIElement *)fb_limitedAccessPromptAlertElement;
++ (nullable XCUIApplication *)fb_limitedAccessPromptApplication;
 
 @end
 

WebDriverAgentLib/Categories/XCUIApplication+FBAlert.m

@@ -24,99 +24,139 @@
 
 @implementation XCUIApplication (FBAlert)
 
-+ (nullable XCUIElement *)fb_limitedAccessPromptAlertElement
++ (nullable XCUIApplication *)fb_limitedAccessPromptApplication
 {
   XCUIApplication *promptApp = [[XCUIApplication alloc] initWithBundleIdentifier:FB_LIMITED_ACCESS_PROMPT_BUNDLE_ID];
-  if (promptApp.state < XCUIApplicationStateRunningForeground) {
-    return nil;
-  }
-  return promptApp.fb_alertElement;
+  return promptApp.state < XCUIApplicationStateRunningForeground ? nil : promptApp;
 }
 
-- (nullable XCUIElement *)fb_alertElementFromSafariWithScrollView:(XCUIElement *)scrollView
-                                                     viewSnapshot:(id<FBXCElementSnapshot>)viewSnapshot
++ (nullable id<FBXCElementSnapshot>)fb_findSafariAlertSnapshotInScrollView:(id<FBXCElementSnapshot>)scrollViewSnapshot
 {
-  CGRect appFrame = viewSnapshot.frame;
-  NSPredicate *dstViewMatchPredicate = [NSPredicate predicateWithBlock:^BOOL(id<FBXCElementSnapshot> snapshot, NSDictionary *bindings) {
-    CGRect curFrame = snapshot.frame;
-    if (!CGRectEqualToRect(appFrame, curFrame)
-        && curFrame.origin.x > 0 && curFrame.size.width < appFrame.size.width) {
-      CGFloat possibleCenterX = (appFrame.size.width - curFrame.size.width) / 2;
-      return fabs(possibleCenterX - curFrame.origin.x) < MAX_CENTER_DELTA;
+  CGRect appFrame = scrollViewSnapshot.frame;
+
+  __block id<FBXCElementSnapshot> webView = nil;
+  [scrollViewSnapshot enumerateDescendantsUsingBlock:^(id<FBXCElementSnapshot> descendant) {
+    if (nil == webView && nil != descendant.identifier && [descendant.identifier isEqualToString:@"WebView"]) {
+      webView = descendant;
     }
-    return NO;
   }];
-  NSPredicate *dstViewContainPredicate1 = [NSPredicate predicateWithFormat:@"elementType == %lu", XCUIElementTypeTextView];
-  NSPredicate *dstViewContainPredicate2 = [NSPredicate predicateWithFormat:@"elementType == %lu", XCUIElementTypeButton];
-  // Find the first XCUIElementTypeOther which is the grandchild of the web view
-  // and is horizontally aligned to the center of the screen
-  XCUIElement *candidate = [[[[[[scrollView descendantsMatchingType:XCUIElementTypeAny]
-       matchingIdentifier:@"WebView"]
-      descendantsMatchingType:XCUIElementTypeOther]
-     matchingPredicate:dstViewMatchPredicate]
-    containingPredicate:dstViewContainPredicate1]
-   containingPredicate:dstViewContainPredicate2].allElementsBoundByIndex.firstObject;
-
-  if (nil == candidate) {
+  if (nil == webView) {
     return nil;
   }
-  // ...and contains one to two buttons
-  // and conatins at least one text view
-  __block NSUInteger buttonsCount = 0;
-  __block NSUInteger textViewsCount = 0;
-  id<FBXCElementSnapshot> snapshot = candidate.fb_cachedSnapshot ?: [candidate fb_customSnapshot];
-  [snapshot enumerateDescendantsUsingBlock:^(id<FBXCElementSnapshot> descendant) {
-    XCUIElementType curType = descendant.elementType;
-    if (curType == XCUIElementTypeButton) {
-      buttonsCount++;
-    } else if (curType == XCUIElementTypeTextView) {
-      textViewsCount++;
+
+  // Find the first XCUIElementTypeOther which is the grandchild of the web view
+  // and is horizontally aligned to the center of the screen, and contains one
+  // to two buttons and at least one text view.
+  __block id<FBXCElementSnapshot> candidate = nil;
+  [webView enumerateDescendantsUsingBlock:^(id<FBXCElementSnapshot> descendant) {
+    if (nil != candidate || descendant.elementType != XCUIElementTypeOther) {
+      return;
+    }
+    CGRect curFrame = descendant.frame;
+    if (CGRectEqualToRect(appFrame, curFrame)
+        || curFrame.origin.x <= 0
+        || curFrame.size.width >= appFrame.size.width) {
+      return;
+    }
+    CGFloat possibleCenterX = (appFrame.size.width - curFrame.size.width) / 2;
+    if (fabs(possibleCenterX - curFrame.origin.x) >= MAX_CENTER_DELTA) {
+      return;
+    }
+
+    __block NSUInteger buttonsCount = 0;
+    __block NSUInteger textViewsCount = 0;
+    [descendant enumerateDescendantsUsingBlock:^(id<FBXCElementSnapshot> innerDescendant) {
+      XCUIElementType curType = innerDescendant.elementType;
+      if (curType == XCUIElementTypeButton) {
+        buttonsCount++;
+      } else if (curType == XCUIElementTypeTextView) {
+        textViewsCount++;
+      }
+    }];
+    if (buttonsCount >= 1 && buttonsCount <= 2 && textViewsCount > 0) {
+      candidate = descendant;
     }
   }];
-  return (buttonsCount >= 1 && buttonsCount <= 2 && textViewsCount > 0) ? candidate : nil;
+  return candidate;
 }
 
-- (XCUIElement *)fb_alertElement
+// Priority matters here: an Alert always wins outright, a Sheet only loses to
+// an Alert, and a ScrollView (the Safari web-alert case) is the last resort.
+// A single tree walk collecting "whichever of these three types shows up
+// first in traversal order" is wrong - a ScrollView or Sheet elsewhere in the
+// tree (e.g. springboard's own UI) can sit earlier than the actual Alert and
+// permanently shadow it, since only one candidate was ever kept.
++ (nullable id<FBXCElementSnapshot>)fb_findAlertSnapshotInApplicationSnapshot:(id<FBXCElementSnapshot>)appSnapshot
 {
-  NSPredicate *alertCollectorPredicate = [NSPredicate predicateWithFormat:@"elementType IN {%lu,%lu,%lu}",
-                                          XCUIElementTypeAlert, XCUIElementTypeSheet, XCUIElementTypeScrollView];
-  XCUIElement *alert = [[self descendantsMatchingType:XCUIElementTypeAny]
-                        matchingPredicate:alertCollectorPredicate].allElementsBoundByIndex.firstObject;
-  if (nil == alert) {
-    return nil;
-  }
-  id<FBXCElementSnapshot> alertSnapshot = alert.fb_cachedSnapshot ?: [alert fb_customSnapshot];
-
-  if (alertSnapshot.elementType == XCUIElementTypeAlert) {
-    return alert;
+  __block id<FBXCElementSnapshot> alertSnapshot = nil;
+  NSMutableArray<id<FBXCElementSnapshot>> *sheetSnapshots = [NSMutableArray array];
+  NSMutableArray<id<FBXCElementSnapshot>> *scrollViewSnapshots = [NSMutableArray array];
+  [appSnapshot enumerateDescendantsUsingBlock:^(id<FBXCElementSnapshot> descendant) {
+    if (nil != alertSnapshot) {
+      return;
+    }
+    switch (descendant.elementType) {
+      case XCUIElementTypeAlert:
+        alertSnapshot = descendant;
+        break;
+      case XCUIElementTypeSheet:
+        [sheetSnapshots addObject:descendant];
+        break;
+      case XCUIElementTypeScrollView:
+        [scrollViewSnapshots addObject:descendant];
+        break;
+      default:
+        break;
+    }
+  }];
+  if (nil != alertSnapshot) {
+    return alertSnapshot;
   }
 
-  if (alertSnapshot.elementType == XCUIElementTypeSheet) {
-    if ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPhone) {
-      return alert;
+  BOOL isPhone = [UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPhone;
+  for (id<FBXCElementSnapshot> sheet in sheetSnapshots) {
+    if (isPhone) {
+      return sheet;
     }
 
     // In case of iPad we want to check if sheet isn't contained by popover.
     // In that case we ignore it.
-    id<FBXCElementSnapshot> ancestor = alertSnapshot.parent;
+    BOOL isInsidePopover = NO;
+    id<FBXCElementSnapshot> ancestor = sheet.parent;
     while (nil != ancestor) {
       if (nil != ancestor.identifier && [ancestor.identifier isEqualToString:@"PopoverDismissRegion"]) {
-        return nil;
+        isInsidePopover = YES;
+        break;
       }
       ancestor = ancestor.parent;
     }
-    return alert;
+    if (!isInsidePopover) {
+      return sheet;
+    }
   }
 
-  if (alertSnapshot.elementType == XCUIElementTypeScrollView) {
-    id<FBXCElementSnapshot> app = [[FBXCElementSnapshotWrapper ensureWrapped:alertSnapshot] fb_parentMatchingType:XCUIElementTypeApplication];
-    if (nil != app && [app.label isEqualToString:FB_SAFARI_APP_NAME]) {
-      // Check alert presence in Safari web view
-      return [self fb_alertElementFromSafariWithScrollView:alert viewSnapshot:alertSnapshot];
+  for (id<FBXCElementSnapshot> scrollView in scrollViewSnapshots) {
+    id<FBXCElementSnapshot> app = [[FBXCElementSnapshotWrapper ensureWrapped:scrollView] fb_parentMatchingType:XCUIElementTypeApplication];
+    if (nil == app || ![app.label isEqualToString:FB_SAFARI_APP_NAME]) {
+      continue;
+    }
+    // Check alert presence in Safari web view
+    id<FBXCElementSnapshot> safariAlert = [self fb_findSafariAlertSnapshotInScrollView:scrollView];
+    if (nil != safariAlert) {
+      return safariAlert;
     }
   }
 
   return nil;
 }
 
+- (nullable id<FBXCElementSnapshot>)fb_alertSnapshot
+{
+  id<FBXCElementSnapshot> appSnapshot = self.fb_cachedSnapshot ?: self.fb_customSnapshot;
+  if (nil == appSnapshot) {
+    return nil;
+  }
+  return [self.class fb_findAlertSnapshotInApplicationSnapshot:appSnapshot];
+}
+
 @end

WebDriverAgentLib/Commands/FBAlertViewCommands.m

@@ -54,19 +54,11 @@ + (NSArray *)routes
     return FBResponseWithStatus([FBCommandStatus invalidArgumentErrorWithMessage:@"Missing 'value' parameter" traceback:nil]);
   }
   FBAlert *alert = [FBAlert alertWithApplication:session.activeApplication];
-  if (!alert.isPresent) {
-    return FBResponseWithStatus([FBCommandStatus noAlertOpenErrorWithMessage:nil
-                                                                   traceback:nil]);
-  }
   NSString *textToType = value;
   if ([value isKindOfClass:[NSArray class]]) {
     textToType = [value componentsJoinedByString:@""];
   }
-  NSError *error;
-  if (![alert typeText:textToType error:&error]) {
-    return FBResponseWithStatus([FBCommandStatus unsupportedOperationErrorWithMessage:error.description
-                                                                            traceback:[NSString stringWithFormat:@"%@", NSThread.callStackSymbols]]);
-  }
+  [alert typeText:textToType];
   return FBResponseWithOK();
 }
 
@@ -75,20 +67,11 @@ + (NSArray *)routes
   XCUIApplication *application = request.session.activeApplication ?: XCUIApplication.fb_activeApplication;
   NSString *name = request.arguments[@"name"];
   FBAlert *alert = [FBAlert alertWithApplication:application];
-  NSError *error;
 
-  if (!alert.isPresent) {
-    return FBResponseWithStatus([FBCommandStatus noAlertOpenErrorWithMessage:nil
-                                                                   traceback:nil]);
-  }
   if (name) {
-    if (![alert clickAlertButton:name error:&error]) {
-      return FBResponseWithStatus([FBCommandStatus invalidElementStateErrorWithMessage:error.description
-                                                                             traceback:[NSString stringWithFormat:@"%@", NSThread.callStackSymbols]]);
-    }
-  } else if (![alert acceptWithError:&error]) {
-    return FBResponseWithStatus([FBCommandStatus invalidElementStateErrorWithMessage:error.description
-                                                                            traceback:[NSString stringWithFormat:@"%@", NSThread.callStackSymbols]]);
+    [alert clickAlertButton:name];
+  } else {
+    [alert accept];
   }
   return FBResponseWithOK();
 }
@@ -98,20 +81,11 @@ + (NSArray *)routes
   XCUIApplication *application = request.session.activeApplication ?: XCUIApplication.fb_activeApplication;
   NSString *name = request.arguments[@"name"];
   FBAlert *alert = [FBAlert alertWithApplication:application];
-  NSError *error;
-
-  if (!alert.isPresent) {
-    return FBResponseWithStatus([FBCommandStatus noAlertOpenErrorWithMessage:nil
-                                                                   traceback:nil]);
-  }
+
   if (name) {
-    if (![alert clickAlertButton:name error:&error]) {
-      return FBResponseWithStatus([FBCommandStatus invalidElementStateErrorWithMessage:error.description
-                                                                            traceback:[NSString stringWithFormat:@"%@", NSThread.callStackSymbols]]);
-    }
-  } else if (![alert dismissWithError:&error]) {
-    return FBResponseWithStatus([FBCommandStatus invalidElementStateErrorWithMessage:error.description
-                                                                            traceback:[NSString stringWithFormat:@"%@", NSThread.callStackSymbols]]);
+    [alert clickAlertButton:name];
+  } else {
+    [alert dismiss];
   }
   return FBResponseWithOK();
 }
@@ -120,11 +94,11 @@ + (NSArray *)routes
   FBSession *session = request.session;
   FBAlert *alert = [FBAlert alertWithApplication:session.activeApplication];
 
-  if (!alert.isPresent) {
+  NSArray *labels = alert.buttonLabels;
+  if (!labels) {
     return FBResponseWithStatus([FBCommandStatus noAlertOpenErrorWithMessage:nil
                                                                    traceback:nil]);
   }
-  NSArray *labels = alert.buttonLabels;
   return FBResponseWithObject(labels);
 }
 @end