As of PSPDFKit 6.8, the PSPDFKit SDK installs an application-wide error handler for SQLite to simplify debugging and indicate potential issues in your setup earlier.
From the official SQLite documentation:
SQLite can be configured to invoke a callback function containing an error code and a terse error message whenever anomalies occur. This mechanism is very helpful in tracking obscure problems that occur rarely and in the field. Application developers are encouraged to take advantage of the error logging facility of SQLite in their products, as it is very low CPU and memory cost but can be a huge aid for debugging.
Installing this error handler happens at the time the license key is set:
sqlite3_config(SQLITE_CONFIG_LOG, pspdf_sqlite_log, nullptr);
Note that this log can be noisy - in particular if your application uses an object-relational mapper such as CoreData on iOS. PSPDFKit filters a few common known, non-problematic messages, however it's likely that there still will be some left.
The logging functionality is a convenience service and can be overridden or disabled at any time. Use following API call to disable logging;
sqlite3_config(SQLITE_CONFIG_LOG, nullptr, nullptr);