Offline full-text search in Android & iOS

MoviesRepository.swift

func search(text: String) -> [Movie] {

    var movies: [Movie] = []
    var statement: OpaquePointer?

    let query = "SELECT title, overview, poster, year, matchinfo(movies, 'pcnalx') FROM movies WHERE movies MATCH '\(text)*'"

    if sqlite3_prepare_v2(db, query, -1, &statement, nil) != SQLITE_OK {
        print("Error preparing select: \(String(cString: sqlite3_errmsg(db)!))")
    }

    while sqlite3_step(statement) == SQLITE_ROW {
        if
            let cTitle = sqlite3_column_text(statement, 0),
            let cOverview = sqlite3_column_text(statement, 1),
            let cPoster = sqlite3_column_text(statement, 2)
        {
            let cYear = sqlite3_column_int64(statement, 3)

            // Read and prepare matchinfo blob
            let buf = sqlite3_column_blob(statement, 4).assumingMemoryBound(to: UInt32.self)
            let blob = [UInt32](UnsafeBufferPointer(start: buf, count: Int(sqlite3_column_bytes(statement, 4))))

            // Calculate score based on matchinfo values
            // Here I'm only using the first column (title) to calculate the score
            let score = OkapiBM25.score(matchinfo: blob, column: 0)

            movies.append(
                Movie(
                    title: String(cString: cTitle),
                    overview: String(cString: cOverview),
                    poster: String(cString: cPoster),
                    year: Int(cYear),
                    score: score
                )
            )

        }
    }

    if sqlite3_finalize(statement) != SQLITE_OK {
        print("Error finalizing prepared statement: \(String(cString: sqlite3_errmsg(db)!))")
    }

    // Sort the movies by the Okapi BM25 score
    return movies.sorted(by: {$0.score > $1.score})
}