I am working on an app that will access an external database that needs to be able to load quickly. This is our own database, and the issue is where to store it for the fastest loading time. Currently, the database resides on a wpengine website, but it loads very slowly. One option is uploading a .plist file sporadically to the user's app when new data is available; it seems like that might not be very secure - although it would probably make accessing the data lightning fast. I was thinking that possibly CloudKit shared storage would be the best place to store the data if I wanted to keep it fast and also keep users from viewing it directly. I would appreciate any thoughts or suggestions.
As far as I understand, CloudKit will be OK for you. You can have a look at NSHipster's excellent summary here. You also have a link to a tutorial in the comments above. If you want to discuss it further, don't hesitate to contact me through chat.