Feat: Multivariate feature flags

PostHog/Classes/PHGPayloadManager.h

@@ -14,6 +14,7 @@ extern NSString *_Nonnull PHGPostHogIntegrationDidStart;
 - (instancetype _Nonnull)initWithPostHog:(PHGPostHog *_Nonnull)posthog;
 
 - (NSArray *_Nonnull)getFeatureFlags;
+- (NSDictionary *_Nonnull)getFlagVariants;
 - (NSDictionary *_Nonnull)getGroups;
 - (void)saveGroup:(NSString *_Nonnull)groupType groupKey:(NSString *_Nonnull)groupKey;
 

PostHog/Classes/PHGPayloadManager.m

@@ -13,16 +13,6 @@
 static NSString *const PHGAnonymousIdKey = @"PHGAnonymousId";
 static NSString *const kPHGAnonymousIdFilename = @"posthog.anonymousId";
 
-static NSString *const PHGActiveFeatureFlags = @"PHGActiveFeatureFlags";
-static NSString *const kPHGActiveFeatureFlags = @"posthog.activeFeatureFlags";
-
-static NSString *const PHGEnabledFeatureFlags = @"PHGEnabledFeatureFlags";
-static NSString *const kPHGEnabledFeatureFlags = @"posthog.enabledFeatureFlags";
-
-static NSString *const PHGGroups = @"PHGGroups";
-static NSString *const kPHGGroups = @"posthog.groups";
-
-
 
 @interface PHGPayloadManager ()
 
@@ -183,19 +173,7 @@ - (void)group:(NSString *)groupType groupKey:(NSString *)groupKey groupPropertie
 
 - (void)receivedFeatureFlags:(NSDictionary *)flags
 {
-    NSArray* keys = [flags allKeys];
-
-#if TARGET_OS_TV
-        [self.userDefaultsStorage setArray:keys forKey:PHGActiveFeatureFlags];
-#else
-        [self.fileStorage setArray:keys forKey:kPHGActiveFeatureFlags];
-#endif
-
-#if TARGET_OS_TV
-        [self.userDefaultsStorage setDictionary:flags forKey:PHGEnabledFeatureFlags];
-#else
-        [self.fileStorage setDictionary:flags forKey:kPHGEnabledFeatureFlags];
-#endif
+    [self.integration receivedFeatureFlags:flags];
 }
 
 - (void)reloadFeatureFlags
@@ -223,12 +201,12 @@ - (void)reloadFeatureFlags
 
 - (NSArray *)getFeatureFlags
 {
-#if TARGET_OS_TV
-    NSArray *keys = [self.userDefaultsStorage arrayForKey:PHGActiveFeatureFlags];
-#else
-    NSArray *keys = [self.fileStorage arrayForKey:kPHGActiveFeatureFlags];
-#endif
-    return keys;
+    return [self.integration getFeatureFlags];
+}
+
+- (NSDictionary *)getFlagVariants
+{
+    return [self.integration getFeatureFlagsAndValues];
 }
 
 - (void)receivedRemoteNotification:(NSDictionary *)userInfo
@@ -315,30 +293,12 @@ - (void)saveAnonymousId:(NSString *)anonymousId
 
 - (void)saveGroup:(NSString *)groupType groupKey:(NSString *)groupKey
 {
-    NSDictionary *currentGroups = [self getGroups];
-    NSMutableDictionary *newGroups = [currentGroups mutableCopy];
-    [newGroups setObject:groupKey forKey:groupType];
-
-#if TARGET_OS_TV
-    [self.userDefaultsStorage setDictionary:newGroups forKey:PHGGroups];
-#else
-    [self.fileStorage setDictionary:newGroups forKey:kPHGGroups];
-#endif
+    [self.integration saveGroup:groupType groupKey:groupKey];
 }
 
 - (NSDictionary *)getGroups
 {
-#if TARGET_OS_TV
-    NSDictionary *groups = [self.userDefaultsStorage dictionaryForKey:PHGGroups];
-#else
-    NSDictionary *groups = [self.fileStorage dictionaryForKey:kPHGGroups];
-#endif
-
-//  if groups doesn't exist, return a new empty dict
-    if (!groups){
-        return [[NSDictionary alloc] init];
-    }
-    return groups;
+    return [self.integration getGroups];
 }
 
 - (void)flush

PostHog/Classes/PHGPostHog.h

@@ -130,6 +130,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (void)group:(NSString *)groupType groupKey:(NSString *)groupKey;
 - (void)group:(NSString *)groupType groupKey:(NSString *)groupKey properties:(SERIALIZABLE_DICT _Nullable)properties;
 
+- (id)getFeatureFlag:(NSString *)flagKey;
 - (bool)isFeatureEnabled:(NSString *)flagKey;
 - (void)reloadFeatureFlags;
 

PostHog/Classes/PHGPostHog.m

@@ -280,10 +280,35 @@ - (void)group:(NSString *_Nonnull)groupType groupKey:(NSString *_Nonnull)groupKe
     }
 }
 
+- (id)getFeatureFlag:(NSString *)flagKey
+{
+    NSDictionary *variants = [self.payloadManager getFlagVariants];
+    id variantValue = [variants valueForKey:flagKey];
+
+    NSMutableDictionary *properties = [NSMutableDictionary dictionary];
+    [properties setValue:flagKey forKey:@"$feature_flag"];
+    [properties setValue:variantValue forKey:@"$feature_flag_response"];
+
+    [self run:PHGEventTypeCapture payload:
+                                    [[PHGCapturePayload alloc] initWithEvent:@"$feature_flag_called"
+                                                                  properties:PHGCoerceDictionary(properties)]];
+    return variantValue;
+}
+
 - (bool)isFeatureEnabled:(NSString *)flagKey
 {
     NSArray *keys = [self.payloadManager getFeatureFlags];
     BOOL isFlagEnabled = [keys containsObject: flagKey];
+
+    NSMutableDictionary *properties = [NSMutableDictionary dictionary];
+
+    [properties setValue:flagKey forKey:@"$feature_flag"];
+    [properties setValue:@(isFlagEnabled) forKey:@"$feature_flag_response"];
+
+    [self run:PHGEventTypeCapture payload:
+                                    [[PHGCapturePayload alloc] initWithEvent:@"$feature_flag_called"
+                                                                  properties:PHGCoerceDictionary(properties)]];
+
     return isFlagEnabled;
 }
 

PostHog/Internal/PHGPostHogIntegration.h

@@ -25,6 +25,13 @@ extern NSString *const PHGPostHogRequestDidFailNotification;
 - (NSDictionary *)liveContext;
 - (void)saveDistinctId:(NSString *)distinctId;
 
+- (NSDictionary *_Nonnull)getGroups;
+- (void)saveGroup:(NSString *_Nonnull)groupType groupKey:(NSString *_Nonnull)groupKey;
+
+- (NSArray *_Nonnull)getFeatureFlags;
+- (NSDictionary *)getFeatureFlagsAndValues;
+- (void)receivedFeatureFlags:(NSDictionary *)flags;
+
 @end
 
 NS_ASSUME_NONNULL_END

PostHog/Internal/PHGPostHogIntegration.m

@@ -31,6 +31,12 @@
 NSString *const kPHGDistinctIdFilename = @"posthog.distinctId";
 NSString *const kPHGQueueFilename = @"posthog.queue.plist";
 
+static NSString *const PHGEnabledFeatureFlags = @"PHGEnabledFeatureFlags";
+static NSString *const kPHGEnabledFeatureFlags = @"posthog.enabledFeatureFlags";
+
+static NSString *const PHGGroups = @"PHGGroups";
+static NSString *const kPHGGroups = @"posthog.groups";
+
 static NSString *GetDeviceModel()
 {
     size_t size;
@@ -217,6 +223,20 @@ - (NSDictionary *)liveContext
         context[@"$network_wifi"] = @NO;
         context[@"$network_cellular"] = @NO;
     }
+
+    context[@"$groups"] = [self getGroups];
+    context[@"$active_feature_flags"] = [self getFeatureFlags];
+
+    NSDictionary *flagsAndValues = [self getFeatureFlagsAndValues];
+
+    int n = 0;
+    for(id flag in flagsAndValues){
+        NSString *key = [NSString stringWithFormat:@"$feature/%@", flag];
+        NSString *enumeratedKey = [NSString stringWithFormat:@"$active_feature_flags__%d", n];
+        context[key] = [flagsAndValues objectForKey:flag];
+        context[enumeratedKey] = flag;
+        n++;
+    }
 
 #if TARGET_OS_IOS
     static dispatch_once_t networkInfoOnceToken;
@@ -569,6 +589,60 @@ - (NSString *)getDistinctId
 #endif
 }
 
+- (void)saveGroup:(NSString *)groupType groupKey:(NSString *)groupKey
+{
+    NSDictionary *currentGroups = [self getGroups];
+    NSMutableDictionary *newGroups = [currentGroups mutableCopy];
+    [newGroups setObject:groupKey forKey:groupType];
+
+#if TARGET_OS_TV
+    [self.userDefaultsStorage setDictionary:newGroups forKey:PHGGroups];
+#else
+    [self.fileStorage setDictionary:newGroups forKey:kPHGGroups];
+#endif
+}
+
+- (NSDictionary *)getGroups
+{
+#if TARGET_OS_TV
+    NSDictionary *groups = [self.userDefaultsStorage dictionaryForKey:PHGGroups];
+#else
+    NSDictionary *groups = [self.fileStorage dictionaryForKey:kPHGGroups];
+#endif
+
+//  if groups doesn't exist, return a new empty dict
+    if (!groups){
+        return [[NSDictionary alloc] init];
+    }
+    return groups;
+}
+
+- (void)receivedFeatureFlags:(NSDictionary *)flags
+{
+#if TARGET_OS_TV
+        [self.userDefaultsStorage setDictionary:flags forKey:PHGEnabledFeatureFlags];
+#else
+        [self.fileStorage setDictionary:flags forKey:kPHGEnabledFeatureFlags];
+#endif
+}
+
+- (NSArray *)getFeatureFlags
+{
+    NSDictionary *dict = [self getFeatureFlagsAndValues];
+    NSArray *keys = [dict allKeys];
+    return keys;
+}
+
+- (NSDictionary *)getFeatureFlagsAndValues
+{
+#if TARGET_OS_TV
+    NSDictionary *dict = [self.userDefaultsStorage dictionaryForKey:PHGEnabledFeatureFlags];
+#else
+    NSDictionary *dict = [self.fileStorage dictionaryForKey:kPHGEnabledFeatureFlags];
+#endif
+    return dict;
+}
+
 - (void)persistQueue
 {
     [self.fileStorage setArray:[self.queue copy] forKey:kPHGQueueFilename];

PostHogTests/FeatureFlagTests.swift

@@ -29,6 +29,28 @@ class FeatureFlagTests: QuickSpec {
       let isEnabled = posthog.isFeatureEnabled("some-flag")
       expect(isEnabled).to(beTrue())
     }
+
+    it("checks multivariate flag is enabled - integer") {
+      _ = stubRequest("POST", "https://app.posthog.test/decide/?v=2" as LSMatcheable)
+        .andReturn(200)?
+        .withBody("{\"featureFlags\":{\"some-flag\":1}}" as LSHTTPBody);
+      posthog.reloadFeatureFlags()
+      // Hacky: Need to buffer for async request to happen without stub being cleaned up
+      sleep(1)
+      let flagValue = posthog.getFeatureFlag("some-flag")
+      expect(flagValue).to(be(1))
+    }
+
+    it("checks multivariate flag is enabled - string") {
+      _ = stubRequest("POST", "https://app.posthog.test/decide/?v=2" as LSMatcheable)
+        .andReturn(200)?
+        .withBody("{\"featureFlags\":{\"some-flag\":\"variant-1\"}}" as LSHTTPBody);
+      posthog.reloadFeatureFlags()
+      // Hacky: Need to buffer for async request to happen without stub being cleaned up
+      sleep(1)
+      let flagValue = posthog.getFeatureFlag("some-flag")
+      expect(flagValue).to(be("variant-1"))
+    }
 
   }