swift

final class MockApiClient: Api {
    
    private static let delay = 5
    
    func fetchMovies(completion: @escaping (Bool, FilmsData?) -> Void) {
        DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(MockApiClient.delay)) {
            // mock your data as before, but now we have a simulated 5-second delay
        }
    }
}