If it’s peppered with place names, it is serving as spyware.
BS. Place names are generally already in the dictionary. Even common surnames and Christian names are already in the dictionary. The cache only retains words not found in the dictionary. Unless you can tell me how your claimed system cache associated with the predictive typing of the iPhone is "spyware" that can be mined by a hacker, you are just trolling. If a hacker can get access to mine that data, then there is a far greater problem than just mining the alphabetic non-contextual words of a cache.