Function than constructs an NSError from the current SQLite3 engine error state in a thread-safe manner.

gistfile1.txt

NSString *SQLiteErrorDomain = @"SQLiteErrorDomain";

NSError *SQLiteError(sqlite3 *db) {
    NSError *error = nil;
    
    if (db) {
        
        /* Lock the database connection to prevent other activity from disturbing the currently recorded internal error code and message. 
         */
        
        sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
        if (mutex) {
            sqlite3_mutex_enter(mutex);
            
            int lastErrorCode = sqlite3_errcode(db);
            const char *lastErrorMessage = sqlite3_errmsg(db);
            
            error = [NSError errorWithDomain:SQLiteErrorDomain code:lastErrorCode userInfo:
                     @{NSLocalizedDescriptionKey : [NSString stringWithUTF8String:lastErrorMessage]}
                     ];
            
            sqlite3_mutex_leave(mutex);
            sqlite3_mutex_free(mutex);
            mutex = NULL;
        }
    }
    
    return error;
}