Sqlite DB Locked

-(void)insertQuery:(NSString *)query{
    sqlite3_stmt *selectstmt;
    // Create a sqlite object.
    sqlite3 *database;
    // Set the database file path.
    NSString *databasePath = [self.documentsDirectory stringByAppendingPathComponent:self.databaseFilename];

    if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) {
        //*************** insert value in database******************************\\

        const char *sql = [query UTF8String];
        sqlite3_prepare_v2(database,sql, -1, &selectstmt, NULL);
        if(sqlite3_step(selectstmt)==SQLITE_DONE)
        {
            NSLog(@"insert successfully");
        }
        else
        {
            NSLog(@"insert not successfully");
            NSLog(@"DB Error: %s", sqlite3_errmsg(database));
        }
        sqlite3_finalize(selectstmt);
    }
    sqlite3_close(database);
}

Using above code trying to fire insert query but sometime it works and most of the time i get DB locked error.

For helping hands Thanks in advance.