ios 11 core spotlight search not working for certain strings

I have succesfully integrated spotlight indexing in my app. Although, its showing most of the passed strings on the Spotlight Search but I am not able to search few of the strings that was in the same array. I created each CSSearchableItemAttributeSet as type kUTTypeText, I set the title with the name that has to appear on the Spotlight Search.


Does the OS take time for indexing? I waited for few days but some of the name hasn't appeared on the search.


Do you have any idea what's happening here?