[iOS] Change theme change event name.
diff --git a/ios/sdk/WeexSDK/Sources/Model/WXSDKInstance.m b/ios/sdk/WeexSDK/Sources/Model/WXSDKInstance.m
index f63097f..803a005 100644
--- a/ios/sdk/WeexSDK/Sources/Model/WXSDKInstance.m
+++ b/ios/sdk/WeexSDK/Sources/Model/WXSDKInstance.m
@@ -1239,7 +1239,7 @@
         
         [[WXSDKManager bridgeMgr] fireEvent:_instanceId
                                         ref:WX_SDK_ROOT_REF
-                                       type:@"themechanged"
+                                       type:@"themechange"
                                      params:@{@"theme": self.themeName?:@"light"}
                                  domChanges:nil];
     }