use backgrounded logic to determine displaying cached IAMs

* Add app backgrounded vs app inactive detection by adding 2 state flags `willResignActiveTriggered` and `didEnterBackgroundTriggered` to track if an app was actually backgrounded or just inactive.
* We will consider the application truly backgrounded if the states are anything except:
- willResignActiveTriggered = TRUE && didEnterBackgroundTriggered = FALSE
* Use backgrounded logic to determine if we should display cached IAMs, as we won't if the app was simply inactive.
* This makes the minimal amount of behavior changes, as there is a lot of existing logic that I don't want to mess around with

Author: nan-li

iOS_SDK/OneSignalSDK/Source/OneSignalLifecycleObserver.m

@@ -90,7 +90,7 @@ - (void)didBecomeActive {
 
 - (void)willResignActive {
     [OneSignal onesignalLog:ONE_S_LL_VERBOSE message:@"application/scene willResignActive"];
-    
+    [OneSignalTracker willResignActiveTriggered];
     if ([OneSignal appId]) {
         [OneSignalTracker onFocus:YES];
         [OneSignal sendTagsOnBackground];
@@ -99,7 +99,7 @@ - (void)willResignActive {
 
 - (void)didEnterBackground {
     [OneSignal onesignalLog:ONE_S_LL_VERBOSE message:@"application/scene didEnterBackground"];
-    
+    [OneSignalTracker didEnterBackgroundTriggered];
     if ([OneSignal appId])
         [OneSignalLocation onFocus:NO];
 }

iOS_SDK/OneSignalSDK/Source/OneSignalTracker.h

@@ -31,5 +31,7 @@
 
 + (void)onFocus:(BOOL)toBackground;
 + (void)onSessionEnded:(NSArray<OSInfluence *> *) lastInfluences;
++ (void)willResignActiveTriggered;
++ (void)didEnterBackgroundTriggered;
 
 @end

iOS_SDK/OneSignalSDK/Source/OneSignalTracker.m

@@ -58,18 +58,29 @@ @implementation OneSignalTracker
 static UIBackgroundTaskIdentifier focusBackgroundTask;
 static NSTimeInterval lastOpenedTime;
 static BOOL lastOnFocusWasToBackground = YES;
+static BOOL willResignActiveTriggered = NO;
+static BOOL didEnterBackgroundTriggered = NO;
 
 + (void)resetLocals {
     [OSFocusTimeProcessorFactory resetUnsentActiveTime];
-     focusBackgroundTask = 0;
+    focusBackgroundTask = 0;
     lastOpenedTime = 0;
     lastOnFocusWasToBackground = YES;
+    [self resetBackgroundDetection];
 }
 
 + (void)setLastOpenedTime:(NSTimeInterval)lastOpened {
     lastOpenedTime = lastOpened;
 }
 
++ (void)willResignActiveTriggered {
+    willResignActiveTriggered = YES;
+}
+
++ (void)didEnterBackgroundTriggered {
+    didEnterBackgroundTriggered = YES;
+}
+
 + (void)beginBackgroundFocusTask {
     focusBackgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
         [OneSignalTracker endBackgroundFocusTask];
@@ -81,10 +92,26 @@ + (void)endBackgroundFocusTask {
     focusBackgroundTask = UIBackgroundTaskInvalid;
 }
 
+/**
+ Returns true if application truly did come from a backgrounded state.
+ Returns false if the application bypassed `didEnterBackground` after entering `willResignActive`.
+ This can happen if the app resumes after a native dialog displays over the app or after the app is in a suspended state and not backgrounded.
+**/
++ (BOOL)applicationForegroundedFromBackgroundedState {
+    return !(willResignActiveTriggered && !didEnterBackgroundTriggered);
+}
+
++ (void)resetBackgroundDetection {
+    willResignActiveTriggered = NO;
+    didEnterBackgroundTriggered = NO;
+}
+
 + (void)onFocus:(BOOL)toBackground {
     // return if the user has not granted privacy permissions
-    if ([OneSignal requiresUserPrivacyConsent])
+    if ([OneSignal requiresUserPrivacyConsent]) {
+        [self resetBackgroundDetection];
         return;
+    }
 
     // Prevent the onFocus to be called twice when app being terminated
     //    - Both WillResignActive and willTerminate
@@ -101,6 +128,10 @@ + (void)onFocus:(BOOL)toBackground {
 
 + (void)applicationForegrounded {
     [OneSignal onesignalLog:ONE_S_LL_DEBUG message:@"Application Foregrounded started"];
+
+    BOOL fromBackgroundedState = [self applicationForegroundedFromBackgroundedState];
+    [self resetBackgroundDetection];
+    
     [OSFocusTimeProcessorFactory cancelFocusCall];
 
     if (OneSignal.appEntryState != NOTIFICATION_CLICK)
@@ -115,7 +146,10 @@ + (void)applicationForegrounded {
         // This checks if notification permissions changed when app was backgrounded
         [OneSignal sendNotificationTypesUpdate];
         [[OSSessionManager sharedSessionManager] attemptSessionUpgrade:OneSignal.appEntryState];
-        [OneSignal receivedInAppMessageJson:nil];
+        if (fromBackgroundedState) {
+            // Use cached IAMs if app truly went into the background
+            [OneSignal receivedInAppMessageJson:nil];
+        }
     }
 
     let wasBadgeSet = [OneSignal clearBadgeCount:false];