Accessing parent class property from child class in Swift

Question

I have two ViewControllers. First is the MoviesVC which shows the lists of movies. The second is the BookmarkedVC which shows the movies which was bookmarked by user.

I have movies:[Movie] property in MoviesVC. Movie class has a bookmark = false flag to determine whether movie is bookmarked or not. When user click bookmark button on cell, I update flag to true.

Since BookmarkedVC is also showing the lists of bookmarked movie, I inherit BookmarkVC: MoviesVC.

In BookmarkedVC viewWillAppear() method, I fetch the bookmarked movies by calling the function below

func loadBookmarkedMovie() -> [Movie] {
    let bookmarkedMovies = self.movies.filter { return $0.bookmark == true }
    return bookmarkedMovies
}

The problem is bookmark of self.movies is still false although they were bookmarked.

To make sure, I call loadBookmarkedMovie() in MoviesVC after I had bookmarked some movies and it actually return the bookmarked movies but in BookmarkedVC it return nil

Have you confirmed that the bookmark property is actually getting changed in your MoviesVC when you interacts with the cell? — Rakshith Nandish, Sep 26 '17 at 05:49
Can i assume that `movies` is initialized when it was declared ? — roy, Sep 26 '17 at 05:52
yeah the property is changed. I check it by calling filter method on array in `viewWillAppear()` — noob, Sep 26 '17 at 05:59
@Roy movies is declared as ? and download movies json from server. — noob, Sep 26 '17 at 06:01
Have a look at: [Apple Developer Link](https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Inheritance.html) — Ganpat, Sep 26 '17 at 06:05
Are you sure it makes to have the `favourite` property reside in the `Movie` objects? For example, what if you eventually introduce multiple users? If a movie is marked favourite, who's favourite is it? — Alexander, Sep 26 '17 at 15:01

roy · Answer 1 · 2017-09-26T06:13:13.017

As a result of Inheritance you only can get properties ( functions and variables ) of Super Class .

So If you inherit MoviesVC . .

Now BookmarkVC has movies:[Movie] (Lets assume movies is initialized when it was declared ) .
All bookmark == false (By default false as you didn't update bookmark yet in BookmarkVC )

So . . func loadBookmarkedMovie() will definitely return nil . To pass data from MoviesVC to BookmarkedVC all you need to use Segue or Delegate .

Accessing parent class property from child class in Swift

1 Answers1