Merge pull request #119 from mixpanel/fix-complicated-property-types

nested dictionary should be a valid type in iOS

Author: zihejia

ios/MixpanelTypeHandler.swift

@@ -47,7 +47,7 @@
             return value.map { mixpanelTypeValue($0) }
 
         case let value as [String: Any]:
-            return value
+            return value.mapValues { mixpanelTypeValue($0) }
 
         case let value as MixpanelType:
             return value