How To Use Fmdb On The Generic Ios Device Instead Of Simulator?

I've created an app using Swift3 and Xcode8, and using FMDB as my database, when it runs on the simulator it can get the data from data.db,but when it runs on the generic device (w

Solution 1:

SQLite offers good error reporting and you should avail yourself of it. So, for example, if any of these executeUpdate calls fail, you should examine the lastErrorMessage (before you close the database) so you know why it failed.

Personally, I'd suggest using executeQuery(_:values:) and executeUpdate(_:values:) rather than executeQuery(_:withArgumentsIn:) and executeUpdate(_:withArgumentsIn:) because the former methods throw errors (which shifts to a more active error handling paradigm from the more passive one in which you have to manually remember to check for errors). But regardless of how you do your error handling, do it, or else we're all guessing.

Personally, I'd suggest using Xcode's "Devices" window and download your app's bundle (see https://stackoverflow.com/a/38064225/1271826) and look at the database. I bet it's a blank database with no tables defined at all. In terms of why, it could be because you did some earlier testing and there's an old version of the database in the Documents folder. Try completely deleting the app from the device and re-running and see if that fixes it.

Other, more obscure sources of problem include filename capitalization (e.g. Data.db vs data.db). The macOS file system will often handle that gracefully because it's not (generally) case sensitive. But iOS devices are case sensitive.

But, like I said, we're flying blind until (a) you add some error handling to your code so you can see why its failing; and (b) look at the database on the device to see what it looks like.